[php] Executing multiple SQL queries in one statement with PHP

You can just add the word JOIN or add a ; after each line(as @pictchubbate said). Better this way because of readability and also you should not meddle DELETE with INSERT; it is easy to go south.

The last question is a matter of debate, but as far as I know yes you should close after a set of queries. This applies mostly to old plain mysql/php and not PDO, mysqli. Things get more complicated(and heated in debates) in these cases.

Finally, I would suggest either using PDO or some other method.