Question

The ‘id’ field of my table auto increases when I insert a row. I want to insert a row and then get that ID.

I would do it just as I said it, but is there a way I can do it without worrying about the time between inserting the row and getting the id?

I know I can query the database for the row that matches the information that was entered, but there is a high change there will be duplicates, with the only difference being the id.

Answer 1

$link = mysqli_connect('127.0.0.1', 'my_user', 'my_pass', 'my_db');
mysqli_query($link, "INSERT INTO mytable (1, 2, 3, 'blah')");
$id = mysqli_insert_id($link);

See mysqli_insert_id().

Whatever you do, don’t insert and then do a "SELECT MAX(id) FROM mytable". Like you say, it’s a race condition and there’s no need. mysqli_insert_id() already has this functionality.

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Another way would be to run both queries in one go, and using MySQL‘s LAST_INSERT_ID() method, where both tables get modified at once (and PHP does not need any ID), like:

mysqli_query($link, "INSERT INTO my_user_table ...;
  INSERT INTO my_other_table (`user_id`) VALUES (LAST_INSERT_ID())");

Note that Each connection keeps track of ID separately (so, conflicts are prevented already).