Use common parent for Db

adminer/include/db.inc.php

@@ -0,0 +1,78 @@
+<?php
+namespace Adminer;
+
+// this could be interface when "Db extends \mysqli" can have compatible type declarations (PHP 7)
+// interfaces can include properties only since PHP 8.4
+abstract class SqlDb {
+	/** @var string */ public $extension; // extension name
+	/** @var string */ public $flavor; // different vendor with the same API, e.g. MariaDB; usually stays empty
+	/** @var string */ public $server_info; // server version
+	/** @var int */ public $affected_rows; // number of affected rows
+	/** @var string */ public $info; // see https://php.net/mysql_info
+	/** @var int */ public $errno; // last error code
+	/** @var string */ public $error; // last error message
+	/** @var Result|bool */ protected $multi; // used for multiquery
+
+	/** Connect to server
+	* @param string
+	* @param string
+	* @param string
+	* @return bool
+	*/
+	abstract function connect($server, $username, $password);
+
+	/** Quote string to use in SQL
+	* @param string
+	* @return string escaped string enclosed in '
+	*/
+	abstract function quote($string);
+
+	/** Select database
+	* @param string
+	* @return bool
+	*/
+	abstract function select_db($database);
+
+	/** Send query
+	* @param string
+	* @param bool
+	* @return Result|bool
+	*/
+	abstract function query($query, $unbuffered = false);
+
+	/** Send query with more resultsets
+	* @param string
+	* @return Result|bool
+	*/
+	function multi_query($query) {
+		return $this->multi = $this->query($query);
+	}
+
+	/** Get current resultset
+	* @return Result|bool
+	*/
+	function store_result() {
+		return $this->multi;
+	}
+
+	/** Fetch next resultset
+	* @return bool
+	*/
+	function next_result() {
+		return false;
+	}
+
+	/** Get single field from result
+	* @param string
+	* @param int
+	* @return string|bool
+	*/
+	function result($query, $field = 0) {
+		$result = $this->query($query);
+		if (!is_object($result)) {
+			return false;
+		}
+		$row = $result->fetch_row();
+		return ($row ? $row[$field] : false);
+	}
+}