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moodle/lib/dml/moodle_database.php

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<?php //$Id$
require_once($CFG->libdir.'/dml/database_column_info.php');
require_once($CFG->libdir.'/dml/moodle_recordset.php');
/// GLOBAL CONSTANTS /////////////////////////////////////////////////////////
/** Bitmask, indicates :name type parameters are supported by db backend. */
define('SQL_PARAMS_NAMED', 1);
/** Bitmask, indicates ? type parameters are supported by db backend. */
define('SQL_PARAMS_QM', 2);
/** Bitmask, indicates $1, $2, ... type parameters are supported by db backend. */
define('SQL_PARAMS_DOLLAR', 4);
/** Normal select query, reading only */
define('SQL_QUERY_SELECT', 1);
/** Insert select query, writing */
define('SQL_QUERY_INSERT', 2);
/** Update select query, writing */
define('SQL_QUERY_UPDATE', 3);
/** Query changing db structure, writing */
define('SQL_QUERY_STRUCTURE', 4);
/** Auxiliary query done by driver, setting connection config, getting table info, etc. */
define('SQL_QUERY_AUX', 5);
/**
* Abstract class representing moodle database interface.
* @package dml
*/
abstract class moodle_database {
// manipulates the db structure
protected $database_manager;
protected $columns = array(); // I wish we had a shared memory cache for this :-(
protected $tables = null;
// db connection options
protected $dbhost;
protected $dbuser;
protected $dbpass;
protected $dbname;
protected $prefix;
/**
* Non-moodle external database used.
*/
protected $external;
/**
* Database or driver specific options, such as sockets or TCPIP db connections
*/
protected $dboptions;
/**
* The database reads (performance counter).
*/
protected $reads = 0;
/**
* The database writes (performance counter).
*/
protected $writes = 0;
/** Debug level */
protected $debug = 0;
protected $last_sql;
protected $last_params;
protected $last_type;
protected $last_extrainfo;
/** internal temporary variable */
private $fix_sql_params_i;
/**
* Contructor - instantiates the database, specifying if it's external (connect to other systems) or no (Moodle DB)
* note this has effect to decide if prefix checks must be performed or no
* @param bool true means external database used
*/
public function __construct($external=false) {
$this->external = $external;
}
/**
* Destructor - cleans up and flushes everything needed.
*/
public function __desctruct() {
$this->dispose();
}
/**
* Detects if all needed PHP stuff installed.
* Note: can be used before connect()
* @return mixed true if ok, string if something
*/
public abstract function driver_installed();
/**
* Returns database table prefix
* Note: can be used before connect()
* @return string database table prefix
*/
public function get_prefix() {
return $this->prefix;
}
/**
* Loads and returns a database instance with the specified type and library.
* @param string $type database type of the driver (mysql, postgres7, mssql, etc)
* @param string $library database library of the driver (adodb, pdo, native, etc)
* @return moodle_database driver object or null if error
*/
public static function get_driver_instance($type, $library) {
global $CFG;
$classname = $type.'_'.$library.'_moodle_database';
$libfile = "$CFG->libdir/dml/$classname.php";
if (!file_exists($libfile)) {
return null;
}
require_once($libfile);
return new $classname();
}
/**
* Returns database family type - describes SQL dialect
* Note: can be used before connect()
* @return string db family name (mysql, postgres, mssql, oracle, etc.)
*/
public abstract function get_dbfamily();
/**
* Returns more specific database driver type
* Note: can be used before connect()
* @return string db type mysql, mysqli, postgres7
*/
protected abstract function get_dbtype();
/**
* Returns general database library name
* Note: can be used before connect()
* @return string db type adodb, pdo, native
*/
protected abstract function get_dblibrary();
/**
* Returns localised database type name
* Note: can be used before connect()
* @return string
*/
public abstract function get_name();
/**
* Returns localised database description
* Note: can be used before connect()
* @return string
*/
public abstract function get_configuration_hints();
/**
* Returns db related part of config.php
* Note: can be used before connect()
* @return string
*/
public function export_dbconfig($dbhost, $dbuser, $dbpass, $dbname, $prefix, array $dboptions=null) {
$this->store_settings($dbhost, $dbuser, $dbpass, $dbname, $prefix, $dboptions);
$cfg = new stdClass();
$cfg->dbtype = $this->get_dbtype();
$cfg->dblibrary = $this->get_dblibrary();
$cfg->dbhost = $this->dbhost;
$cfg->dbname = $this->dbname;
$cfg->dbuser = $this->dbuser;
$cfg->dbpass = $this->dbpass;
$cfg->prefix = $this->prefix;
if ($this->dboptions) {
$cfg->dboptions = $this->dboptions;
}
return $cfg;
}
/**
* Connect to db
* Must be called before other methods.
* @param string $dbhost
* @param string $dbuser
* @param string $dbpass
* @param string $dbname
* @param mixed $prefix string means moodle db prefix, false used for external databases where prefix not used
* @param array $dboptions driver specific options
* @return bool true
* @throws dml_connection_exception if error
*/
public abstract function connect($dbhost, $dbuser, $dbpass, $dbname, $prefix, array $dboptions=null);
/**
* Store various database settings
* @param string $dbhost
* @param string $dbuser
* @param string $dbpass
* @param string $dbname
* @param mixed $prefix string means moodle db prefix, false used for external databases where prefix not used
* @param array $dboptions driver specific options
* @return void
*/
protected function store_settings($dbhost, $dbuser, $dbpass, $dbname, $prefix, array $dboptions=null) {
$this->dbhost = $dbhost;
$this->dbuser = $dbuser;
$this->dbpass = $dbpass;
$this->dbname = $dbname;
$this->prefix = $prefix;
$this->dboptions = (array)$dboptions;
}
/**
* Attempt to create the database
* @param string $dbhost
* @param string $dbuser
* @param string $dbpass
* @param string $dbname
*
* @return bool success
*/
public function create_database($dbhost, $dbuser, $dbpass, $dbname) {
return false;
}
/**
* Close database connection and release all resources
* and memory (especially circular memory references).
* Do NOT use connect() again, create a new instance if needed.
*/
public function dispose() {
if ($this->database_manager) {
$this->database_manager->dispose();
$this->database_manager = null;
}
$this->columns = array();
$this->tables = null;
}
/**
* Called before each db query.
* @param string $sql
* @param array array of parameters
* @param int $type type of query
* @param mixed $extrainfo driver specific extra information
* @return void
*/
protected function query_start($sql, array $params=null, $type, $extrainfo=null) {
$this->last_sql = $sql;
$this->last_params = $params;
$this->last_type = $type;
$this->last_extrainfo = $extrainfo;
switch ($type) {
case SQL_QUERY_SELECT:
case SQL_QUERY_AUX:
$this->reads++;
break;
case SQL_QUERY_INSERT:
case SQL_QUERY_UPDATE:
case SQL_QUERY_STRUCTURE:
$this->writes++;
}
$this->print_debug($sql, $params);
}
/**
* Called immediately after each db query.
* @param mixed db specific result
* @return void
*/
protected function query_end($result) {
if ($result !== false) {
return;
}
switch ($this->last_type) {
case SQL_QUERY_SELECT:
case SQL_QUERY_AUX:
throw new dml_read_exception($this->get_last_error(), $this->last_sql, $this->last_params);
case SQL_QUERY_INSERT:
case SQL_QUERY_UPDATE:
throw new dml_write_exception($this->get_last_error(), $this->last_sql, $this->last_params);
case SQL_QUERY_STRUCTURE:
$this->get_manager(); // includes ddl exceptions classes ;-)
throw new ddl_change_structure_exception($this->get_last_error(), $this->last_sql);
}
}
/**
* Returns database server info array
* @return array
*/
public abstract function get_server_info();
/**
* Returns supported query parameter types
* @return bitmask
*/
protected abstract function allowed_param_types();
/**
* Returns last error reported by database engine.
*/
public abstract function get_last_error();
/**
* Print sql debug info
* @param string $sql query which caused problems
* @param array $params optional query parameters
* @param mixed $obj optional library specific object
*/
protected function print_debug($sql, array $params=null, $obj=null) {
if (!$this->get_debug()) {
return;
}
//TODO: detect CLI mode and skip s() ;-)
echo "<hr />\n";
echo s($sql)."\n";
if (!is_null($params)) {
echo "[".s(var_export($params, true))."]\n";
}
echo "<hr />\n";
}
/**
* Returns SQL WHERE conditions.
*
* @param array conditions - must not contain numeric indexes
* @return array sql part and params
*/
protected function where_clause(array $conditions=null) {
$allowed_types = $this->allowed_param_types();
if (empty($conditions)) {
return array('', array());
}
$where = array();
$params = array();
foreach ($conditions as $key=>$value) {
if (is_int($key)) {
throw new dml_exception('invalidnumkey');
}
if (is_null($value)) {
$where[] = "$key IS NULL";
} else {
if ($allowed_types & SQL_PARAMS_NAMED) {
$where[] = "$key = :$key";
$params[$key] = $value;
} else {
$where[] = "$key = ?";
$params[] = $value;
}
}
}
$where = implode(" AND ", $where);
return array($where, $params);
}
/**
* Returns SQL WHERE conditions for the ..._list methods.
*
* @param string $field the name of a field.
* @param array $values the values field might take.
* @return array sql part and params
*/
protected function where_clause_list($field, array $values) {
$params = array();
$select = array();
$values = (array)$values;
foreach ($values as $value) {
if (is_bool($value)) {
$value = (int)$value;
}
if (is_null($value)) {
$select[] = "$field IS NULL";
} else {
$select[] = "$field = ?";
$params[] = $value;
}
}
$select = implode(" OR ", $select);
return array($select, $params);
}
/**
* Constructs IN() or = sql fragment
* @param mixed $items single or array of values
* @param int $type bound param type SQL_PARAMS_QM or SQL_PARAMS_NAMED
* @param string named param placeholder start
* @param bool true means equal, false not equal
* @return array - $sql and $params
*/
public function get_in_or_equal($items, $type=SQL_PARAMS_QM, $start='param0000', $equal=true) {
if ($type == SQL_PARAMS_QM) {
if (!is_array($items) or count($items) == 1) {
$sql = $equal ? '= ?' : '<> ?';
$items = (array)$items;
$params = array_values($items);
} else {
if ($equal) {
$sql = 'IN ('.implode(',', array_fill(0, count($items), '?')).')';
} else {
$sql = 'NOT IN ('.implode(',', array_fill(0, count($items), '?')).')';
}
$params = array_values($items);
}
} else if ($type == SQL_PARAMS_NAMED) {
if (!is_array($items)){
$sql = $equal ? "= :$start" : "<> :$start";
$params = array($start=>$items);
} else if (count($items) == 1) {
$sql = $equal ? "= :$start" : "<> :$start";
$item = reset($items);
$params = array($start=>$item);
} else {
$params = array();
$sql = array();
foreach ($items as $item) {
$params[$start] = $item;
$sql[] = ':'.$start++;
}
if ($equal) {
$sql = 'IN ('.implode(',', $sql).')';
} else {
$sql = 'NOT IN ('.implode(',', $sql).')';
}
}
} else {
throw new dml_exception('typenotimplement');
}
return array($sql, $params);
}
/**
* Converts short table name {tablename} to real table name
* @param string sql
* @return string sql
*/
protected function fix_table_names($sql) {
return preg_replace('/\{([a-z][a-z0-9_]*)\}/', $this->prefix.'$1', $sql);
}
/** Internal function */
private function _fix_sql_params_dollar_callback($match) {
$this->fix_sql_params_i++;
return "\$".$this->fix_sql_params_i;
}
/**
* Normalizes sql query parameters and verifies parameters.
* @param string $sql query or part of it
* @param array $params query parameters
*/
public function fix_sql_params($sql, array $params=null) {
$params = (array)$params; // mke null array if needed
$allowed_types = $this->allowed_param_types();
// convert table names
$sql = $this->fix_table_names($sql);
// NICOLAS C: Fixed regexp for negative backwards lookahead of double colons. Thanks for Sam Marshall's help
$named_count = preg_match_all('/(?<!:):[a-z][a-z0-9_]*/', $sql, $named_matches); // :: used in pgsql casts
$dollar_count = preg_match_all('/\$[1-9][0-9]*/', $sql, $dollar_matches);
$q_count = substr_count($sql, '?');
$count = 0;
if ($named_count) {
$type = SQL_PARAMS_NAMED;
$count = $named_count;
}
if ($dollar_count) {
if ($count) {
throw new dml_exception('mixedtypesqlparam');
}
$type = SQL_PARAMS_DOLLAR;
$count = $dollar_count;
}
if ($q_count) {
if ($count) {
throw new dml_exception('mixedtypesqlparam');
}
$type = SQL_PARAMS_QM;
$count = $q_count;
}
if (!$count) {
// ignore params
if ($allowed_types & SQL_PARAMS_NAMED) {
return array($sql, array(), SQL_PARAMS_NAMED);
} else if ($allowed_types & SQL_PARAMS_QM) {
return array($sql, array(), SQL_PARAMS_QM);
} else {
return array($sql, array(), SQL_PARAMS_DOLLAR);
}
}
if ($count > count($params)) {
$a = new stdClass;
$a->expected = $count;
$a->actual = count($params);
throw new dml_exception('invalidqueryparam', $a);
}
$target_type = $allowed_types;
if ($type & $allowed_types) { // bitwise AND
if ($count == count($params)) {
if ($type == SQL_PARAMS_QM) {
return array($sql, array_values($params), SQL_PARAMS_QM); // 0-based array required
} else {
//better do the validation of names below
}
}
// needs some fixing or validation - there might be more params than needed
$target_type = $type;
}
if ($type == SQL_PARAMS_NAMED) {
$finalparams = array();
foreach ($named_matches[0] as $key) {
$key = trim($key, ':');
if (!array_key_exists($key, $params)) {
throw new dml_exception('missingkeyinsql', $key, '');
}
$finalparams[$key] = $params[$key];
}
if ($count != count($finalparams)) {
throw new dml_exception('duplicateparaminsql');
}
if ($target_type & SQL_PARAMS_QM) {
$sql = preg_replace('/(?<!:):[a-z][a-z0-9_]*/', '?', $sql);
return array($sql, array_values($finalparams), SQL_PARAMS_QM); // 0-based required
} else if ($target_type & SQL_PARAMS_NAMED) {
return array($sql, $finalparams, SQL_PARAMS_NAMED);
} else { // $type & SQL_PARAMS_DOLLAR
//lambda-style functions eat memory - we use globals instead :-(
$this->fix_sql_params_i = 0;
$sql = preg_replace_callback('/(?<!:):[a-z][a-z0-9_]*/', array($this, '_fix_sql_params_dollar_callback'), $sql);
return array($sql, array_values($finalparams), SQL_PARAMS_DOLLAR); // 0-based required
}
} else if ($type == SQL_PARAMS_DOLLAR) {
if ($target_type & SQL_PARAMS_DOLLAR) {
return array($sql, array_values($params), SQL_PARAMS_DOLLAR); // 0-based required
} else if ($target_type & SQL_PARAMS_QM) {
$sql = preg_replace('/\$[0-9]+/', '?', $sql);
return array($sql, array_values($params), SQL_PARAMS_QM); // 0-based required
} else { //$target_type & SQL_PARAMS_NAMED
$sql = preg_replace('/\$([0-9]+)/', ':param\\1', $sql);
$finalparams = array();
foreach ($params as $key=>$param) {
$key++;
$finalparams['param'.$key] = $param;
}
return array($sql, $finalparams, SQL_PARAMS_NAMED);
}
} else { // $type == SQL_PARAMS_QM
if (count($params) != $count) {
$params = array_slice($params, 0, $count);
}
if ($target_type & SQL_PARAMS_QM) {
return array($sql, array_values($params), SQL_PARAMS_QM); // 0-based required
} else if ($target_type & SQL_PARAMS_NAMED) {
$finalparams = array();
$pname = 'param0';
$parts = explode('?', $sql);
$sql = array_shift($parts);
foreach ($parts as $part) {
$param = array_shift($params);
$pname++;
$sql .= ':'.$pname.$part;
$finalparams[$pname] = $param;
}
return array($sql, $finalparams, SQL_PARAMS_NAMED);
} else { // $type & SQL_PARAMS_DOLLAR
//lambda-style functions eat memory - we use globals instead :-(
$this->fix_sql_params_i = 0;
$sql = preg_replace_callback('/\?/', array($this, '_fix_sql_params_dollar_callback'), $sql);
return array($sql, array_values($params), SQL_PARAMS_DOLLAR); // 0-based required
}
}
}
/**
* Return tables in database WITHOUT current prefix
* @return array of table names in lowercase and without prefix
*/
public abstract function get_tables($usecache=true);
/**
* Return table indexes - everything lowercased
* @return array of arrays
*/
public abstract function get_indexes($table);
/**
* Returns datailed information about columns in table. This information is cached internally.
* @param string $table name
* @param bool $usecache
* @return array array of database_column_info objects indexed with column names
*/
public abstract function get_columns($table, $usecache=true);
/**
* Reset internal column details cache
* @param string $table - empty means all, or one if name of table given
* @return void
*/
public function reset_caches() {
$this->columns = array();
$this->tables = null;
}
/**
* Returns sql generator used for db manipulation.
* Used mostly in upgrade.php scripts.
* @return object database_manager instance
*/
public function get_manager() {
global $CFG;
if (!$this->database_manager) {
require_once($CFG->libdir.'/ddllib.php');
$classname = $this->get_dbfamily().'_sql_generator';
require_once("$CFG->libdir/ddl/$classname.php");
$generator = new $classname($this);
$this->database_manager = new database_manager($this, $generator);
}
return $this->database_manager;
}
/**
* Attempt to change db encoding toUTF-8 if poossible
* @return bool success
*/
public function change_db_encoding() {
return false;
}
/**
* Is db in unicode mode?
* @return bool
*/
public function setup_is_unicodedb() {
return true;
}
/**
* Enable/disable very detailed debugging
* @param bool $state
*/
public function set_debug($state) {
$this->debug = $state;
}
/**
* Returns debug status
* @return bool $state
*/
public function get_debug() {
return $this->debug;
}
/**
* Enable/disable detailed sql logging
* @param bool $state
*/
public function set_logging($state) {
// TODO: adodb sql logging shares one table without prefix per db - this is no longer acceptable :-(
// we must create one table shared by all drivers
}
/**
* Do NOT use in code, to be used by database_manager only!
* @param string $sql query
* @return bool true
* @throws dml_exception if error
*/
public abstract function change_database_structure($sql);
/**
* Execute general sql query. Should be used only when no other method suitable.
* Do NOT use this to make changes in db structure, use database_manager::execute_sql() instead!
* @param string $sql query
* @param array $params query parameters
* @return bool true
* @throws dml_exception if error
*/
public abstract function execute($sql, array $params=null);
/**
* Get a number of records as a moodle_recordset where all the given conditions met.
*
* Selects records from the table $table.
*
* If specified, only records meeting $conditions.
*
* If specified, the results will be sorted as specified by $sort. This
* is added to the SQL as "ORDER BY $sort". Example values of $sort
* mightbe "time ASC" or "time DESC".
*
* If $fields is specified, only those fields are returned.
*
* Since this method is a little less readable, use of it should be restricted to
* code where it's possible there might be large datasets being returned. For known
* small datasets use get_records - it leads to simpler code.
*
* If you only want some of the records, specify $limitfrom and $limitnum.
* The query will skip the first $limitfrom records (according to the sort
* order) and then return the next $limitnum records. If either of $limitfrom
* or $limitnum is specified, both must be present.
*
* The return value is a moodle_recordset
* if the query succeeds. If an error occurrs, false is returned.
*
* @param string $table the table to query.
* @param array $conditions optional array $fieldname=>requestedvalue with AND in between
* @param string $sort an order to sort the results in (optional, a valid SQL ORDER BY parameter).
* @param string $fields a comma separated list of fields to return (optional, by default all fields are returned).
* @param int $limitfrom return a subset of records, starting at this point (optional, required if $limitnum is set).
* @param int $limitnum return a subset comprising this many records (optional, required if $limitfrom is set).
* @return object moodle_recordset instance
* @throws dml_exception if error
*/
public function get_recordset($table, array $conditions=null, $sort='', $fields='*', $limitfrom=0, $limitnum=0) {
list($select, $params) = $this->where_clause($conditions);
return $this->get_recordset_select($table, $select, $params, $sort, $fields, $limitfrom, $limitnum);
}
/**
* Get a number of records as a moodle_recordset where one field match one list of values.
*
* Only records where $field takes one of the values $values are returned.
* $values must be an array of values.
*
* Other arguments and the return type as for @see function get_recordset.
*
* @param string $table the table to query.
* @param string $field a field to check (optional).
* @param array $values array of values the field must have
* @param string $sort an order to sort the results in (optional, a valid SQL ORDER BY parameter).
* @param string $fields a comma separated list of fields to return (optional, by default all fields are returned).
* @param int $limitfrom return a subset of records, starting at this point (optional, required if $limitnum is set).
* @param int $limitnum return a subset comprising this many records (optional, required if $limitfrom is set).
* @return object moodle_recordset instance
* @throws dml_exception if error
*/
public function get_recordset_list($table, $field, array $values, $sort='', $fields='*', $limitfrom=0, $limitnum=0) {
list($select, $params) = $this->where_clause_list($field, $values);
if (empty($select)) {
$select = '? = ?'; /// Fake condition, won't return rows ever. MDL-17645
$params = array(1, 2);
}
return $this->get_recordset_select($table, $select, $params, $sort, $fields, $limitfrom, $limitnum);
}
/**
* Get a number of records as a moodle_recordset which match a particular WHERE clause.
*
* If given, $select is used as the SELECT parameter in the SQL query,
* otherwise all records from the table are returned.
*
* Other arguments and the return type as for @see function get_recordset.
*
* @param string $table the table to query.
* @param string $select A fragment of SQL to be used in a where clause in the SQL call.
* @param array $params array of sql parameters
* @param string $sort an order to sort the results in (optional, a valid SQL ORDER BY parameter).
* @param string $fields a comma separated list of fields to return (optional, by default all fields are returned).
* @param int $limitfrom return a subset of records, starting at this point (optional, required if $limitnum is set).
* @param int $limitnum return a subset comprising this many records (optional, required if $limitfrom is set).
* @return object moodle_recordset instance
* @throws dml_exception if error
*/
public function get_recordset_select($table, $select, array $params=null, $sort='', $fields='*', $limitfrom=0, $limitnum=0) {
$sql = "SELECT $fields FROM {".$table."}";
if ($select) {
$sql .= " WHERE $select";
}
if ($sort) {
$sql .= " ORDER BY $sort";
}
return $this->get_recordset_sql($sql, $params, $limitfrom, $limitnum);
}
/**
* Get a number of records as a moodle_recordset using a SQL statement.
*
* Since this method is a little less readable, use of it should be restricted to
* code where it's possible there might be large datasets being returned. For known
* small datasets use get_records_sql - it leads to simpler code.
*
* The return type is as for @see function get_recordset.
*
* @param string $sql the SQL select query to execute.
* @param array $params array of sql parameters
* @param int $limitfrom return a subset of records, starting at this point (optional, required if $limitnum is set).
* @param int $limitnum return a subset comprising this many records (optional, required if $limitfrom is set).
* @return object moodle_recordset instance
* @throws dml_exception if error
*/
public abstract function get_recordset_sql($sql, array $params=null, $limitfrom=0, $limitnum=0);
/**
* Get a number of records as an array of objects where all the given conditions met.
*
* If the query succeeds and returns at least one record, the
* return value is an array of objects, one object for each
* record found. The array key is the value from the first
* column of the result set. The object associated with that key
* has a member variable for each column of the results.
*
* @param string $table the table to query.
* @param array $conditions optional array $fieldname=>requestedvalue with AND in between
* @param string $sort an order to sort the results in (optional, a valid SQL ORDER BY parameter).
* @param string $fields a comma separated list of fields to return (optional, by default
* all fields are returned). The first field will be used as key for the
* array so must be a unique field such as 'id'.
* @param int $limitfrom return a subset of records, starting at this point (optional, required if $limitnum is set).
* @param int $limitnum return a subset comprising this many records (optional, required if $limitfrom is set).
* @return array of objects indexed by first column
* @throws dml_exception if error
*/
public function get_records($table, array $conditions=null, $sort='', $fields='*', $limitfrom=0, $limitnum=0) {
list($select, $params) = $this->where_clause($conditions);
return $this->get_records_select($table, $select, $params, $sort, $fields, $limitfrom, $limitnum);
}
/**
* Get a number of records as an array of objects where one field match one list of values.
*
* Return value as for @see function get_records.
*
* @param string $table The database table to be checked against.
* @param string $field The field to search
* @param string $values array of values
* @param string $sort Sort order (as valid SQL sort parameter)
* @param string $fields A comma separated list of fields to be returned from the chosen table. If specified,
* the first field should be a unique one such as 'id' since it will be used as a key in the associative
* array.
* @return array of objects indexed by first column
* @throws dml_exception if error
*/
public function get_records_list($table, $field, array $values, $sort='', $fields='*', $limitfrom=0, $limitnum=0) {
list($select, $params) = $this->where_clause_list($field, $values);
if (empty($select)) {
// nothing to return
return array();
}
return $this->get_records_select($table, $select, $params, $sort, $fields, $limitfrom, $limitnum);
}
/**
* Get a number of records as an array of objects which match a particular WHERE clause.
*
* Return value as for @see function get_records.
*
* @param string $table the table to query.
* @param string $select A fragment of SQL to be used in a where clause in the SQL call.
* @param array $params array of sql parameters
* @param string $sort an order to sort the results in (optional, a valid SQL ORDER BY parameter).
* @param string $fields a comma separated list of fields to return
* (optional, by default all fields are returned). The first field will be used as key for the
* array so must be a unique field such as 'id'.
* @param int $limitfrom return a subset of records, starting at this point (optional, required if $limitnum is set).
* @param int $limitnum return a subset comprising this many records (optional, required if $limitfrom is set).
* @return array of objects indexed by first column
* @throws dml_exception if error
*/
public function get_records_select($table, $select, array $params=null, $sort='', $fields='*', $limitfrom=0, $limitnum=0) {
if ($select) {
$select = "WHERE $select";
}
if ($sort) {
$sort = " ORDER BY $sort";
}
return $this->get_records_sql("SELECT $fields FROM {$this->prefix}$table $select $sort", $params, $limitfrom, $limitnum);
}
/**
* Get a number of records as an array of objects using a SQL statement.
*
* Return value as for @see function get_records.
*
* @param string $sql the SQL select query to execute. The first column of this SELECT statement
* must be a unique value (usually the 'id' field), as it will be used as the key of the
* returned array.
* @param array $params array of sql parameters
* @param int $limitfrom return a subset of records, starting at this point (optional, required if $limitnum is set).
* @param int $limitnum return a subset comprising this many records (optional, required if $limitfrom is set).
* @return array of objects indexed by first column
* @throws dml_exception if error
*/
public abstract function get_records_sql($sql, array $params=null, $limitfrom=0, $limitnum=0);
/**
* Get the first two columns from a number of records as an associative array where all the given conditions met.
*
* Arguments as for @see function get_recordset.
*
* If no errors occur the return value
* is an associative whose keys come from the first field of each record,
* and whose values are the corresponding second fields.
* False is returned if an error occurs.
*
* @param string $table the table to query.
* @param array $conditions optional array $fieldname=>requestedvalue with AND in between
* @param string $sort an order to sort the results in (optional, a valid SQL ORDER BY parameter).
* @param string $fields a comma separated list of fields to return - the number of fields should be 2!
* @param int $limitfrom return a subset of records, starting at this point (optional, required if $limitnum is set).
* @param int $limitnum return a subset comprising this many records (optional, required if $limitfrom is set).
* @return array an associative array
* @throws dml_exception if error
*/
public function get_records_menu($table, array $conditions=null, $sort='', $fields='*', $limitfrom=0, $limitnum=0) {
$menu = array();
if ($records = $this->get_records($table, $conditions, $sort, $fields, $limitfrom, $limitnum)) {
foreach ($records as $record) {
$record = (array)$record;
$key = array_shift($record);
$value = array_shift($record);
$menu[$key] = $value;
}
}
return $menu;
}
/**
* Get the first two columns from a number of records as an associative array which match a particular WHERE clause.
*
* Arguments as for @see function get_recordset_select.
* Return value as for @see function get_records_menu.
*
* @param string $table The database table to be checked against.
* @param string $select A fragment of SQL to be used in a where clause in the SQL call.
* @param array $params array of sql parameters
* @param string $sort Sort order (optional) - a valid SQL order parameter
* @param string $fields A comma separated list of fields to be returned from the chosen table - the number of fields should be 2!
* @param int $limitfrom return a subset of records, starting at this point (optional, required if $limitnum is set).
* @param int $limitnum return a subset comprising this many records (optional, required if $limitfrom is set).
* @return array an associative array
* @throws dml_exception if error
*/
public function get_records_select_menu($table, $select, array $params=null, $sort='', $fields='*', $limitfrom=0, $limitnum=0) {
$menu = array();
if ($records = $this->get_records_select($table, $select, $params, $sort, $fields, $limitfrom, $limitnum)) {
foreach ($records as $record) {
$record = (array)$record;
$key = array_shift($record);
$value = array_shift($record);
$menu[$key] = $value;
}
}
return $menu;
}
/**
* Get the first two columns from a number of records as an associative array using a SQL statement.
*
* Arguments as for @see function get_recordset_sql.
* Return value as for @see function get_records_menu.
*
* @param string $sql The SQL string you wish to be executed.
* @param array $params array of sql parameters
* @param int $limitfrom return a subset of records, starting at this point (optional, required if $limitnum is set).
* @param int $limitnum return a subset comprising this many records (optional, required if $limitfrom is set).
* @return array an associative array
* @throws dml_exception if error
*/
public function get_records_sql_menu($sql, array $params=null, $limitfrom=0, $limitnum=0) {
$menu = array();
if ($records = $this->get_records_sql($sql, $params, $limitfrom, $limitnum)) {
foreach ($records as $record) {
$record = (array)$record;
$key = array_shift($record);
$value = array_shift($record);
$menu[$key] = $value;
}
}
return $menu;
}
/**
* Get a single database record as an object where all the given conditions met.
*
* @param string $table The table to select from.
* @param array $conditions optional array $fieldname=>requestedvalue with AND in between
* @param string $fields A comma separated list of fields to be returned from the chosen table.
* @param bool $ignoremultiple ignore multiple records if found
* @return maixed a fieldset object containing the first mathcing record or false if not found
* @throws dml_exception if error
*/
public function get_record($table, array $conditions, $fields='*', $ignoremultiple=false) {
list($select, $params) = $this->where_clause($conditions);
return $this->get_record_select($table, $select, $params, $fields, $ignoremultiple);
}
/**
* Get a single database record as an object which match a particular WHERE clause.
*
* @param string $table The database table to be checked against.
* @param string $select A fragment of SQL to be used in a where clause in the SQL call.
* @param array $params array of sql parameters
* @param string $fields A comma separated list of fields to be returned from the chosen table.
* @param bool $ignoremultiple ignore multiple records if found
* @return maixed a fieldset object containing the first mathcing record or false if not found
* @throws dml_exception if error
*/
public function get_record_select($table, $select, array $params=null, $fields='*', $ignoremultiple=false) {
if ($select) {
$select = "WHERE $select";
}
return $this->get_record_sql("SELECT $fields FROM {$this->prefix}$table $select", $params, $ignoremultiple);
}
/**
* Get a single database record as an object using a SQL statement.
*
* The SQL statement should normally only return one record. In debug mode
* you will get a warning if more records are found. In non-debug mode,
* it just returns the first record.
*
* Use get_records_sql() if more matches possible!
*
* @param string $sql The SQL string you wish to be executed, should normally only return one record.
* @param array $params array of sql parameters
* @param bool $ignoremultiple ignore multiple records if found
* @return maixed a fieldset object containing the first mathcing record or false if not found
* @throws dml_exception if error
*/
public function get_record_sql($sql, array $params=null, $ignoremultiple=false) {
$count = $ignoremultiple ? 1 : 2;
if (!$records = $this->get_records_sql($sql, $params, 0, $count)) {
// not found
return false;
}
if (!$ignoremultiple and count($records) > 1) {
debugging('Error: mdb->get_record() found more than one record!');
}
$return = reset($records);
return $return;
}
/**
* Get a single field value from a table record where all the given conditions met.
*
* @param string $table the table to query.
* @param string $return the field to return the value of.
* @param array $conditions optional array $fieldname=>requestedvalue with AND in between
* @return mixed the specified value false if not found
* @throws dml_exception if error
*/
public function get_field($table, $return, array $conditions) {
list($select, $params) = $this->where_clause($conditions);
return $this->get_field_select($table, $return, $select, $params);
}
/**
* Get a single field value from a table record which match a particular WHERE clause.
*
* @param string $table the table to query.
* @param string $return the field to return the value of.
* @param string $select A fragment of SQL to be used in a where clause returning one row with one column
* @param array $params array of sql parameters
* @return mixed the specified value false if not found
* @throws dml_exception if error
*/
public function get_field_select($table, $return, $select, array $params=null) {
if ($select) {
$select = "WHERE $select";
}
return $this->get_field_sql("SELECT $return FROM {" . $table . "} $select", $params);
}
/**
* Get a single field value (first field) using a SQL statement.
*
* @param string $table the table to query.
* @param string $return the field to return the value of.
* @param string $sql The SQL query returning one row with one column
* @param array $params array of sql parameters
* @return mixed the specified value false if not found
* @throws dml_exception if error
*/
public function get_field_sql($sql, array $params=null) {
if ($records = $this->get_records_sql($sql, $params, 0, 1)) {
$record = reset($records);
$record = (array)$record;
return reset($record); // first column
}
return false;
}
/**
* Selects records and return values of chosen field as an array which match a particular WHERE clause.
*
* @param string $table the table to query.
* @param string $return the field we are intered in
* @param string $select A fragment of SQL to be used in a where clause in the SQL call.
* @param array $params array of sql parameters
* @return mixed array of values
* @throws dml_exception if error
*/
public function get_fieldset_select($table, $return, $select, array $params=null) {
if ($select) {
$select = "WHERE $select";
}
return $this->get_fieldset_sql("SELECT $return FROM {$this->prefix}$table $select", $params);
}
/**
* Selects records and return values (first field) as an array using a SQL statement.
*
* @param string $sql The SQL query
* @param array $params array of sql parameters
* @return mixed array of values
* @throws dml_exception if error
*/
public abstract function get_fieldset_sql($sql, array $params=null);
/**
* Insert new record into database, as fast as possible, no safety checks, lobs not supported.
* @param string $table name
* @param mixed $params data record as object or array
* @param bool $returnit return it of inserted record
* @param bool $bulk true means repeated inserts expected
* @param bool $customsequence true if 'id' included in $params, disables $returnid
* @return mixed true or new id
* @throws dml_exception if error
*/
public abstract function insert_record_raw($table, $params, $returnid=true, $bulk=false, $customsequence=false);
/**
* Insert a record into a table and return the "id" field if required.
*
* Some conversions and safety checks are carried out. Lobs are supported.
* If the return ID isn't required, then this just reports success as true/false.
* $data is an object containing needed data
* @param string $table The database table to be inserted into
* @param object $data A data object with values for one or more fields in the record
* @param bool $returnid Should the id of the newly created record entry be returned? If this option is not requested then true/false is returned.
* @return mixed true or new id
* @throws dml_exception if error
*/
public abstract function insert_record($table, $dataobject, $returnid=true, $bulk=false);
/**
* Import a record into a table, id field is required.
* Safety checks are NOT carried out. Lobs are supported.
*
* @param string $table name of database table to be inserted into
* @param object $dataobject A data object with values for one or more fields in the record
* @return bool true
* @throws dml_exception if error
*/
public abstract function import_record($table, $dataobject);
/**
* Update record in database, as fast as possible, no safety checks, lobs not supported.
* @param string $table name
* @param mixed $params data record as object or array
* @param bool true means repeated updates expected
* @return bool true
* @throws dml_exception if error
*/
public abstract function update_record_raw($table, $params, $bulk=false);
/**
* Update a record in a table
*
* $dataobject is an object containing needed data
* Relies on $dataobject having a variable "id" to
* specify the record to update
*
* @param string $table The database table to be checked against.
* @param object $dataobject An object with contents equal to fieldname=>fieldvalue. Must have an entry for 'id' to map to the table specified.
* @param bool true means repeated updates expected
* @return bool true
* @throws dml_exception if error
*/
public abstract function update_record($table, $dataobject, $bulk=false);
/**
* Set a single field in every table record where all the given conditions met.
*
* @param string $table The database table to be checked against.
* @param string $newfield the field to set.
* @param string $newvalue the value to set the field to.
* @param array $conditions optional array $fieldname=>requestedvalue with AND in between
* @return bool true
* @throws dml_exception if error
*/
public function set_field($table, $newfield, $newvalue, array $conditions=null) {
list($select, $params) = $this->where_clause($conditions);
return $this->set_field_select($table, $newfield, $newvalue, $select, $params);
}
/**
* Set a single field in every table record which match a particular WHERE clause.
*
* @param string $table The database table to be checked against.
* @param string $newfield the field to set.
* @param string $newvalue the value to set the field to.
* @param string $select A fragment of SQL to be used in a where clause in the SQL call.
* @param array $params array of sql parameters
* @return bool true
* @throws dml_exception if error
*/
public abstract function set_field_select($table, $newfield, $newvalue, $select, array $params=null);
/**
* Count the records in a table where all the given conditions met.
*
* @param string $table The table to query.
* @param array $conditions optional array $fieldname=>requestedvalue with AND in between
* @return int The count of records returned from the specified criteria.
* @throws dml_exception if error
*/
public function count_records($table, array $conditions=null) {
list($select, $params) = $this->where_clause($conditions);
return $this->count_records_select($table, $select, $params);
}
/**
* Count the records in a table which match a particular WHERE clause.
*
* @param string $table The database table to be checked against.
* @param string $select A fragment of SQL to be used in a WHERE clause in the SQL call.
* @param array $params array of sql parameters
* @param string $countitem The count string to be used in the SQL call. Default is COUNT('x').
* @return int The count of records returned from the specified criteria.
* @throws dml_exception if error
*/
public function count_records_select($table, $select, array $params=null, $countitem="COUNT('x')") {
if ($select) {
$select = "WHERE $select";
}
return $this->count_records_sql("SELECT $countitem FROM {$this->prefix}$table $select", $params);
}
/**
* Get the result of a SQL SELECT COUNT(...) query.
*
* Given a query that counts rows, return that count. (In fact,
* given any query, return the first field of the first record
* returned. However, this method should only be used for the
* intended purpose.) If an error occurrs, 0 is returned.
*
* @param string $sql The SQL string you wish to be executed.
* @param array $params array of sql parameters
* @return int the count
* @throws dml_exception if error
*/
public function count_records_sql($sql, array $params=null) {
if ($count = $this->get_field_sql($sql, $params)) {
return $count;
} else {
return 0;
}
}
/**
* Test whether a record exists in a table where all the given conditions met.
*
* The record to test is specified by giving up to three fields that must
* equal the corresponding values.
*
* @param string $table The table to check.
* @param array $conditions optional array $fieldname=>requestedvalue with AND in between
* @return bool true if a matching record exists, else false.
* @throws dml_exception if error
*/
public function record_exists($table, array $conditions) {
list($select, $params) = $this->where_clause($conditions);
return $this->record_exists_select($table, $select, $params);
}
/**
* Test whether any records exists in a table which match a particular WHERE clause.
*
* @param string $table The database table to be checked against.
* @param string $select A fragment of SQL to be used in a WHERE clause in the SQL call.
* @param array $params array of sql parameters
* @return bool true if a matching record exists, else false.
* @throws dml_exception if error
*/
public function record_exists_select($table, $select, array $params=null) {
if ($select) {
$select = "WHERE $select";
}
return $this->record_exists_sql("SELECT 'x' FROM {$this->prefix}$table $select", $params);
}
/**
* Test whether a SQL SELECT statement returns any records.
*
* This function returns true if the SQL statement executes
* without any errors and returns at least one record.
*
* @param string $sql The SQL statement to execute.
* @param array $params array of sql parameters
* @return bool true if the SQL executes without errors and returns at least one record.
* @throws dml_exception if error
*/
public function record_exists_sql($sql, array $params=null) {
if ($mrs = $this->get_recordset_sql($sql, $params, 0, 1)) {
$return = $mrs->valid();
$mrs->close();
return $return;
}
return false;
}
/**
* Delete the records from a table where all the given conditions met.
* If conditions not specified, table is truncated.
*
* @param string $table the table to delete from.
* @param array $conditions optional array $fieldname=>requestedvalue with AND in between
* @return bool true.
* @throws dml_exception if error
*/
public function delete_records($table, array $conditions=null) {
if (is_null($conditions)) {
return $this->execute("TRUNCATE TABLE {".$table."}");
}
list($select, $params) = $this->where_clause($conditions);
return $this->delete_records_select($table, $select, $params);
}
/**
* Delete the records from a table where one field match one list of values.
*
* @param string $table the table to delete from.
* @param string $field The field to search
* @param string $values array of values
* @return bool true.
* @throws dml_exception if error
*/
public function delete_records_list($table, $field, array $values) {
list($select, $params) = $this->where_clause_list($field, $values);
if (empty($select)) {
// nothing to delete
return true;
}
return $this->delete_records_select($table, $select, $params);
}
/**
* Delete one or more records from a table which match a particular WHERE clause.
*
* @param string $table The database table to be checked against.
* @param string $select A fragment of SQL to be used in a where clause in the SQL call (used to define the selection criteria).
* @param array $params array of sql parameters
* @return bool true.
* @throws dml_exception if error
*/
public abstract function delete_records_select($table, $select, array $params=null);
/// sql contructs
/**
* Returns the FROM clause required by some DBs in all SELECT statements.
*
* To be used in queries not having FROM clause to provide cross_db
* Most DBs don't need it, hence the default is ''
*/
public function sql_null_from_clause() {
return '';
}
/**
* Returns the SQL text to be used in order to perform one bitwise AND operation
* between 2 integers.
*
* NOTE: The SQL result is a number and can not be used directly in
* SQL condition, please compare it to some number to get a bool!!
*
* @param integer int1 first integer in the operation
* @param integer int2 second integer in the operation
* @return string the piece of SQL code to be used in your statement
*/
public function sql_bitand($int1, $int2) {
return '((' . $int1 . ') & (' . $int2 . '))';
}
/**
* Returns the SQL text to be used in order to perform one bitwise NOT operation
* with 1 integer.
*
* @param integer int1 integer in the operation
* @return string the piece of SQL code to be used in your statement.
*/
public function sql_bitnot($int1) {
return '(~(' . $int1 . '))';
}
/**
* Returns the SQL text to be used in order to perform one bitwise OR operation
* between 2 integers.
*
* NOTE: The SQL result is a number and can not be used directly in
* SQL condition, please compare it to some number to get a bool!!
*
* @param integer int1 first integer in the operation
* @param integer int2 second integer in the operation
* @return string the piece of SQL code to be used in your statement.
*/
public function sql_bitor($int1, $int2) {
return '((' . $int1 . ') | (' . $int2 . '))';
}
/**
* Returns the SQL text to be used in order to perform one bitwise XOR operation
* between 2 integers.
*
* NOTE: The SQL result is a number and can not be used directly in
* SQL condition, please compare it to some number to get a bool!!
*
* @param integer int1 first integer in the operation
* @param integer int2 second integer in the operation
* @return string the piece of SQL code to be used in your statement.
*/
public function sql_bitxor($int1, $int2) {
return '((' . $int1 . ') ^ (' . $int2 . '))';
}
/**
* Returns the SQL text to be used in order to perform module '%'
* opration - remainder after division
*
* @param integer int1 first integer in the operation
* @param integer int2 second integer in the operation
* @return string the piece of SQL code to be used in your statement.
*/
public function sql_modulo($int1, $int2) {
return '((' . $int1 . ') % (' . $int2 . '))';
}
/**
* Returns the correct CEIL expression applied to fieldname.
*
* @param string fieldname the field (or expression) we are going to ceil
* @return string the piece of SQL code to be used in your ceiling statement
* Most DB use CEIL(), hence it's the default.
*/
public function sql_ceil($fieldname) {
return ' CEIL(' . $fieldname . ')';
}
/**
* Returns the SQL to be used in order to CAST one CHAR column to INTEGER.
*
* Be aware that the CHAR column you're trying to cast contains really
* int values or the RDBMS will throw an error!
*
* @param string fieldname the name of the field to be casted
* @param boolean text to specify if the original column is one TEXT (CLOB) column (true). Defaults to false.
* @return string the piece of SQL code to be used in your statement.
*/
public function sql_cast_char2int($fieldname, $text=false) {
return ' ' . $fieldname . ' ';
}
/**
* Returns the SQL to be used in order to CAST one CHAR column to REAL number.
*
* Be aware that the CHAR column you're trying to cast contains really
* numbers or the RDBMS will throw an error!
*
* @param string fieldname the name of the field to be casted
* @param boolean text to specify if the original column is one TEXT (CLOB) column (true). Defaults to false.
* @return string the piece of SQL code to be used in your statement.
*/
public function sql_cast_char2real($fieldname, $text=false) {
return ' ' . $fieldname . ' ';
}
/**
* Returns the SQL text to be used to compare one TEXT (clob) column with
* one varchar column, because some RDBMS doesn't support such direct
* comparisons.
*
* @param string fieldname the name of the TEXT field we need to order by
* @param string number of chars to use for the ordering (defaults to 32)
* @return string the piece of SQL code to be used in your statement.
*/
public function sql_compare_text($fieldname, $numchars=32) {
return $this->sql_order_by_text($fieldname, $numchars);
}
/**
* Returns the proper SQL to do LIKE in a case-insensitive way.
*
* Note the LIKE are case sensitive for Oracle. Oracle 10g is required to use
* the caseinsensitive search using regexp_like() or NLS_COMP=LINGUISTIC :-(
* See http://docs.moodle.org/en/XMLDB_Problems#Case-insensitive_searches
*
* @return string
*/
public function sql_ilike() {
return 'LIKE';
}
/**
* Returns the proper SQL to do CONCAT between the elements passed
* Can take many parameters
*
* @param string $element
* @return string
*/
public abstract function sql_concat();
/**
* Returns the proper SQL to do CONCAT between the elements passed
* with a given separator
*
* @param string $separator
* @param array $elements
* @return string
*/
public abstract function sql_concat_join($separator="' '", $elements=array());
/**
* Returns the proper SQL (for the dbms in use) to concatenate $firstname and $lastname
* TODO: Does this really need to be here? Eloy 20070727.
*
* @param string $firstname User's first name
* @param string $lastname User's last name
* @return string
*/
function sql_fullname($first='firstname', $last='lastname') {
return $this->sql_concat($first, "' '", $last);
}
/**
* Returns the SQL text to be used to order by one TEXT (clob) column, because
* some RDBMS doesn't support direct ordering of such fields.
*
* Note that the use or queries being ordered by TEXT columns must be minimised,
* because it's really slooooooow.
* @param string fieldname the name of the TEXT field we need to order by
* @param string number of chars to use for the ordering (defaults to 32)
* @return string the piece of SQL code to be used in your statement.
*/
public function sql_order_by_text($fieldname, $numchars=32) {
return $fieldname;
}
/**
* Returns the proper substr() function for each DB.
* NOTE: this was originally returning only function name
*
* @param string $expr some string field, no aggregates
* @param mixed $start integer or expresion evaluating to int (1 based value; first char has index 1)
* @param mixed $length optional integer or expresion evaluating to int
* @return string sql fragment
*/
public function sql_substr($expr, $start, $length=false) {
if (count(func_get_args()) < 2) {
throw new coding_exception('moodle_database::sql_substr() requires at least two parameters', 'Originaly this function was only returning name of SQL substring function, it now requires all parameters.');
}
if ($length === false) {
return "SUBSTR($expr, $start)";
} else {
return "SUBSTR($expr, $start, $length)";
}
}
/**
* Returns the SQL for returning searching one string for the location of another.
* Note, there is no guarantee which order $needle, $haystack will be in
* the resulting SQL, so when using this method, and both arguments contain
* placeholders, you should use named placeholders.
* @param string $needle the SQL expression that will be searched for.
* @param string $haystack the SQL expression that will be searched in.
* @return string the required SQL
*/
public function sql_position($needle, $haystack) {
// Implementation using standard SQL.
return "POSITION(($needle) IN ($haystack))";
}
/**
* Returns the empty string char used by every supported DB. To be used when
* we are searching for that values in our queries. Only Oracle uses this
* for now (will be out, once we migrate to proper NULLs if that days arrives)
*/
function sql_empty() {
return '';
}
/**
* Returns the proper SQL to know if one field is empty.
*
* Note that the function behavior strongly relies on the
* parameters passed describing the field so, please, be accurate
* when speciffying them.
*
* Also, note that this function is not suitable to look for
* fields having NULL contents at all. It's all for empty values!
*
* This function should be applied in all the places where conditins of
* the type:
*
* ... AND fieldname = '';
*
* are being used. Final result should be:
*
* ... AND ' . sql_isempty('tablename', 'fieldname', true/false, true/false);
*
* (see parameters description below)
*
* @param string $tablename name of the table (without prefix). Not used for now but can be
* necessary in the future if we want to use some introspection using
* meta information against the DB. /// TODO ///
* @param string $fieldname name of the field we are going to check
* @param boolean $nullablefield to specify if the field us nullable (true) or no (false) in the DB
* @param boolean $textfield to specify if it is a text (also called clob) field (true) or a varchar one (false)
* @return string the sql code to be added to check for empty values
*/
public function sql_isempty($tablename, $fieldname, $nullablefield, $textfield) {
return " $fieldname = '' ";
}
/**
* Returns the proper SQL to know if one field is not empty.
*
* Note that the function behavior strongly relies on the
* parameters passed describing the field so, please, be accurate
* when speciffying them.
*
* This function should be applied in all the places where conditions of
* the type:
*
* ... AND fieldname != '';
*
* are being used. Final result should be:
*
* ... AND ' . sql_isnotempty('tablename', 'fieldname', true/false, true/false);
*
* (see parameters description below)
*
* @param string $tablename name of the table (without prefix). Not used for now but can be
* necessary in the future if we want to use some introspection using
* meta information against the DB. /// TODO ///
* @param string $fieldname name of the field we are going to check
* @param boolean $nullablefield to specify if the field us nullable (true) or no (false) in the DB
* @param boolean $textfield to specify if it is a text (also called clob) field (true) or a varchar one (false)
* @return string the sql code to be added to check for non empty values
*/
public function sql_isnotempty($tablename, $fieldname, $nullablefield, $textfield) {
return ' ( NOT ' . $this->sql_isempty($tablename, $fieldname, $nullablefield, $textfield) . ') ';
}
/**
* Does this driver suppoer regex syntax when searching
*/
public function sql_regex_supported() {
return false;
}
/**
* Return regex positive or negative match sql
* @param bool $positivematch
* @return string or empty if not supported
*/
public function sql_regex($positivematch=true) {
return '';
}
/// transactions
/**
* on DBs that support it, switch to transaction mode and begin a transaction
* you'll need to ensure you call commit_sql() or your changes *will* be lost.
*
* this is _very_ useful for massive updates
*/
public function begin_sql() {
return false;
}
/**
* on DBs that support it, commit the transaction
*/
public function commit_sql() {
return false;
}
/**
* on DBs that support it, rollback the transaction
*/
public function rollback_sql() {
return false;
}
/// performance and logging
/**
* Returns number of reads done by this database
* @return int
*/
public function perf_get_reads() {
return $this->reads;
}
/**
* Returns number of writes done by this database
* @return int
*/
public function perf_get_writes() {
return $this->writes;
}
/**
* Returns number of queries done by this database
* @return int
*/
public function perf_get_queries() {
return $this->writes + $this->reads;
}
}
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