Question

I’m coding using PHP PDO and MySQL.

In that context, can I write a single transaction that would run a first query (or series of queries), and then use the result of this query as an input into another query?

For example, I would like to (1) create a new record in table A and get the autoincremented ID in return, (2) create a new record in table B and get the autoincremented ID in return, (3) enter the IDs generated above from table A and B in two fields of a table C which represents the relation between A and B.

Can I do the above in a single transaction? Also, can I add some programming between each queries?

Answer 1

Short answer: Yes.

Long answer:

Absolutely, that’s what transactions are designed for.

As far as your SQL vendor supports transaction (mysql does on InnoDB tables) you can use them to execute a serie of query.

Also, can I add some programming between each queries?

Yes, you can, however, make sure that if you’re updating some third party, to rollback the change yourself.

Example:

try {
  $db->beginTransaction();
  $db->exec('INSERT INTO tableA (id, column) VALUES (NULL, NOW())');
  $db->exec('SELECT id FROM tableB ORDER BY id DESC LIMIT 1');
  // ...
  $httpClient->post(sprintf('/notify/foo/%d?value=ok', $id));
  $db->commit();
} catch (\PDOException $e) {
    $db->rollback();
    $httpClient->post(sprintf('/notify/foo/%d?value=cancel', $id));
} 

Note that you can aslo nest transaction and use SAVEPOINT on InnoDB tables.