To change MySQL databases within code use the mysql_select_db() function like this:
<?php
mysql_select_db(‘db_2′, $mysql_link);
$query = “SELECT username from user where userid = ‘$user_id’”;
$result = mysql_query($query,$mysql_link);
if(mysql_num_rows($result)) {
$row = mysql_fetch_row($result);
$username = $row[0];
}
mysql_select_db(‘db_1′, $mysql_link);
?>
mysql_select_db(‘db_2′, $mysql_link);
$query = “SELECT username from user where userid = ‘$user_id’”;
$result = mysql_query($query,$mysql_link);
if(mysql_num_rows($result)) {
$row = mysql_fetch_row($result);
$username = $row[0];
}
mysql_select_db(‘db_1′, $mysql_link);
?>
This code checks db_2 for the username by $user_id.
