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MDL-14679 fixing limitfrom, limitnum queries under pgsql, mssql and oracle
This commit is contained in:
stronk7
parent
bb1dff214d
commit
72a3902f5a
@ -700,12 +700,11 @@ class mssql_native_moodle_database extends moodle_database {
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$limitfrom = ($limitfrom < 0) ? 0 : $limitfrom;
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$limitnum = ($limitnum < 0) ? 0 : $limitnum;
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if ($limitfrom or $limitnum) {
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if ($limitnum < 1) {
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$limitnum = "18446744073709551615";
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if ($limitnum >= 1) { // Only apply TOP clause if we have any limitnum (limitfrom offset is hadled later)
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$fetch = $limitfrom + $limitnum;
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$sql = preg_replace('/^([\s(])*SELECT( DISTINCT)?(?!\s*TOP\s*\()/i',
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"\\1SELECT\\2 TOP $fetch", $sql);
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}
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$fetch = $limitfrom + $limitnum;
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$sql = preg_replace('/^([\s(])*SELECT( DISTINCT)?(?!\s*TOP\s*\()/i',
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"\\1SELECT\\2 TOP $fetch", $sql);
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}
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list($sql, $params, $type) = $this->fix_sql_params($sql, $params);
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@ -715,7 +714,7 @@ class mssql_native_moodle_database extends moodle_database {
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$result = mssql_query($rawsql, $this->mssql);
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$this->query_end($result);
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if ($limitfrom) {
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if ($limitfrom) { // Skip $limitfrom records
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mssql_data_seek($result, $limitfrom);
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}
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@ -655,6 +655,52 @@ class oci_native_moodle_database extends moodle_database {
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return $value;
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}
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/**
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* Transforms the sql and params in order to emulate the LIMIT clause available in other DBs
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*
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* @param string $sql the SQL select query to execute.
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* @param array $params array of sql parameters
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* @param int $limitfrom return a subset of records, starting at this point (optional, required if $limitnum is set).
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* @param int $limitnum return a subset comprising this many records (optional, required if $limitfrom is set).
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* @return array with the transformed sql and params updated
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*/
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private function get_limit_sql($sql, array $params = null, $limitfrom=0, $limitnum=0) {
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$limitfrom = (int)$limitfrom;
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$limitnum = (int)$limitnum;
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$limitfrom = ($limitfrom < 0) ? 0 : $limitfrom;
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$limitnum = ($limitnum < 0) ? 0 : $limitnum;
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// TODO: Add the /*+ FIRST_ROWS */ hint if there isn't another hint
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if ($limitfrom and $limitnum) {
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$sql = "SELECT oracle_o.*
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FROM (SELECT oracle_i.*, rownum AS oracle_rownum
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FROM ($sql) oracle_i
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WHERE rownum <= :oracle_num_rows
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) oracle_o
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WHERE oracle_rownum > :oracle_skip_rows";
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$params['oracle_num_rows'] = $limitfrom + $limitnum;
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$params['oracle_skip_rows'] = $limitfrom;
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} else if ($limitfrom and !$limitnum) {
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$sql = "SELECT oracle_o.*
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FROM (SELECT oracle_i.*, rownum AS oracle_rownum
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FROM ($sql) oracle_i
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) oracle_o
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WHERE oracle_rownum > :oracle_skip_rows";
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$params['oracle_skip_rows'] = $limitfrom;
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} else if (!$limitfrom and $limitnum) {
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$sql = "SELECT *
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FROM ($sql)
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WHERE rownum <= :oracle_num_rows";
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$params['oracle_num_rows'] = $limitnum;
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}
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return array($sql, $params);
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}
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/**
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* This function will handle all the column values before being inserted/updated to DB for Oracle
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* installations. This is because the "special feature" of Oracle where the empty string is
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@ -829,6 +875,7 @@ class oci_native_moodle_database extends moodle_database {
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// TODO: Optimise
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oci_bind_by_name($stmt, $key, $params[$key]);
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break;
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case 'N':
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case 'F':
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// TODO: Optimise
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@ -836,13 +883,13 @@ class oci_native_moodle_database extends moodle_database {
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break;
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case 'B':
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// TODO: Shouldn't arrive here ever! Blobs already bound above. Exception!
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break;
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// TODO: Only arrive here if BLOB is null: Bind if so, else exception!
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// don't break here
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case 'X':
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if (strlen($value) > 4000) {
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// TODO: Shouldn't arrive here ever! BIG Clobs already bound above. Exception!
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}
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// TODO: Only arrive here if CLOB is null or <= 4000 cc, else exception
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// don't break here
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default: // Bind as CHAR (applying dirty hack)
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// TODO: Optimise
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oci_bind_by_name($stmt, $key, $this->oracle_dirty_hack($tablename, $key, $params[$key]));
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@ -945,39 +992,10 @@ class oci_native_moodle_database extends moodle_database {
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* @throws dml_exception if error
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*/
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public function get_recordset_sql($sql, array $params=null, $limitfrom=0, $limitnum=0) {
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$limitfrom = (int)$limitfrom;
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$limitnum = (int)$limitnum;
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$limitfrom = ($limitfrom < 0) ? 0 : $limitfrom;
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$limitnum = ($limitnum < 0) ? 0 : $limitnum;
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list($sql, $params, $type) = $this->fix_sql_params($sql, $params);
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if ($limitfrom and $limitnum) {
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$rawsql = "SELECT oracle_o.*
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FROM (SELECT oracle_i.*, rownum AS oracle_rownum
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FROM ($sql) oracle_i
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) oracle_o
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WHERE rownum <= :oracle_max AND oracle_rownum > :oracle_min";
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$params['oracle_max'] = $limitfrom + $limitnum;
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$params['oracle_min'] = $limitfrom;
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} else if ($limitfrom and !$limitnum) {
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$rawsql = "SELECT oracle_o.*
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FROM (SELECT oracle_i.*, rownum AS oracle_rownum
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FROM ($sql) oracle_i
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) oracle_o
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WHERE oracle_rownum > :oracle_min";
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$params['oracle_min'] = $limitfrom;
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} else if (!$limitfrom and $limitnum) {
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$rawsql = "SELECT *
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FROM ($sql)
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WHERE rownum <= :oracle_max";
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$params['oracle_max'] = $limitnum;
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} else { // No limitfrom nor limitnum
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$rawsql = $sql;
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}
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list($rawsql, $params) = $this->get_limit_sql($sql, $params, $limitfrom, $limitnum);
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$this->query_start($sql, $params, SQL_QUERY_SELECT);
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$stmt = $this->parse_query($rawsql);
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@ -1007,39 +1025,13 @@ class oci_native_moodle_database extends moodle_database {
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* @throws dml_exception if error
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*/
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public function get_records_sql($sql, array $params=null, $limitfrom=0, $limitnum=0) {
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$limitfrom = (int)$limitfrom;
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$limitnum = (int)$limitnum;
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$limitfrom = ($limitfrom < 0) ? 0 : $limitfrom;
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$limitnum = ($limitnum < 0) ? 0 : $limitnum;
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list($sql, $params, $type) = $this->fix_sql_params($sql, $params);
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if ($limitfrom and $limitnum) {
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$sql = "SELECT oracle_o.*
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FROM (SELECT oracle_i.*, rownum AS oracle_rownum
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FROM ($sql) oracle_i
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) oracle_o
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WHERE rownum <= :oracle_max AND oracle_rownum > :oracle_min";
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$params['oracle_max'] = $limitfrom + $limitnum;
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$params['oracle_min'] = $limitfrom;
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} else if ($limitfrom and !$limitnum) {
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$sql = "SELECT oracle_o.*
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FROM (SELECT oracle_i.*, rownum AS oracle_rownum
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FROM ($sql) oracle_i
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) oracle_o
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WHERE oracle_rownum > :oracle_min";
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$params['oracle_min'] = $limitfrom;
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} else if (!$limitfrom and $limitnum) {
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$sql = "SELECT *
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FROM ($sql)
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WHERE rownum <= :oracle_max";
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$params['oracle_max'] = $limitnum;
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}
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list($rawsql, $params) = $this->get_limit_sql($sql, $params, $limitfrom, $limitnum);
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$this->query_start($sql, $params, SQL_QUERY_SELECT);
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$stmt = $this->parse_query($sql);
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$stmt = $this->parse_query($rawsql);
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$this->bind_params($stmt, $params);
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$result = oci_execute($stmt, $this->commit_status);
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$this->query_end($result, $stmt);
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@ -585,7 +585,7 @@ class pgsql_native_moodle_database extends moodle_database {
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$limitnum = ($limitnum < 0) ? 0 : $limitnum;
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if ($limitfrom or $limitnum) {
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if ($limitnum < 1) {
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$limitnum = "18446744073709551615";
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$limitnum = "ALL";
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}
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$sql .= " LIMIT $limitnum OFFSET $limitfrom";
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}
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@ -624,7 +624,7 @@ class pgsql_native_moodle_database extends moodle_database {
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$limitnum = ($limitnum < 0) ? 0 : $limitnum;
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if ($limitfrom or $limitnum) {
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if ($limitnum < 1) {
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$limitnum = "18446744073709551615";
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$limitnum = "ALL";
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}
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$sql .= " LIMIT $limitnum OFFSET $limitfrom";
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}
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