mysql_select_db

(PHP 4, PHP 5)

mysql_select_db — Select a MySQL database

Warning

This extension was deprecated in PHP 5.5.0, and it was removed in PHP 7.0.0. Instead, the MySQLi or PDO_MySQL extension should be used. See also MySQL: choosing an API guide. Alternatives to this function include:

mysqli_select_db()
PDO::__construct() (part of dsn)

Description

mysql_select_db(string $database_name, resource $link_identifier = NULL): bool

Sets the current active database on the server that's associated with the specified link identifier. Every subsequent call to mysql_query() will be made on the active database.

Parameters

database_name: The name of the database that is to be selected.
link_identifier: The MySQL connection. If the link identifier is not specified, the last link opened by mysql_connect() is assumed. If no such link is found, it will try to create one as if mysql_connect() had been called with no arguments. If no connection is found or established, an E_WARNING level error is generated.

Return Values

Returns true on success or false on failure.

Examples

Example #1 mysql_select_db() example

<?php

$link = mysql_connect('localhost', 'mysql_user', 'mysql_password');
if (!$link) {
    die('Not connected : ' . mysql_error());
}

// make foo the current db
$db_selected = mysql_select_db('foo', $link);
if (!$db_selected) {
    die ('Can\'t use foo : ' . mysql_error());
}
?>

Notes

Note:
For backward compatibility, the following deprecated alias may be used: mysql_selectdb()

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User Contributed Notes 2 notes

down

james at gogo dot co dot nz ¶

20 years ago

Be carefull if you are using two databases on the same server at the same time.  By default mysql_connect returns the same connection ID for multiple calls with the same server parameters, which means if you do 

<?php
  $db1 = mysql_connect(...stuff...);
  $db2 = mysql_connect(...stuff...);
  mysql_select_db('db1', $db1);
  mysql_select_db('db2', $db2); 
?>

then $db1 will actually have selected the database 'db2', because the second call to mysql_connect just returned the already opened connection ID !

You have two options here, eiher you have to call mysql_select_db before each query you do, or if you're using php4.2+ there is a parameter to mysql_connect to force the creation of a new link.