MySQL: Multiple queries simultaneously in PHP and phpMyAdmin

I want to run multiple MySQL commands at once. So far, I have done that with phpMyAdmin and separately for each statement with a semicolon. Like this:

UPDATE tab SET age=24 WHERE id=1;
UPDATE tab SET age=68 WHERE id=2;

Now I want to execute the same command in PHP and I have been thinking of the following solution:

$query = "UPDATE tab SET age=24 WHERE id=1;
          UPDATE tab SET age=68 WHERE id=2;";
 
mysql_db_query($database, $query, $connection);

Unfortunately, this leads always to an error. It is not wanting to work! And I don't know why. The same MySQL command is still working also in phpMyAdmin! Why would it suddenly stop working in PHP?