CODEWITHSUNDEEP
phpdatabase
Jason Strat
Jason Strat

Reputation:

Can mysql_insert_id mix up things?

I have two tables in my database 'file' and 'message'. If a user submit a file I first submit the file name in the file table, location and so on in my database. After that I inmedietley set the following variable:

 $file_id = mysql_insert_id();

This will get the assigned id of the the file, with that variable I can the insert it into the message table, such as message_file_id. That way I can get message file, with just an id.

All is working, but my question is. If I were to have 2 users submit a message with a file at the same time (which would be hard, or even impossible) is there a possibility user A gets user B file id?

There is variable that could affect this like a user having faster or slower time than another.

Upvotes: 0

Views: 55

Answers (1)

CFL_Jeff
CFL_Jeff

Reputation: 2719

No, there is no chance User A will get User B's file ID as long as both transactions were performed in the same connection. MySQL is smart enough to give out distinct auto-increment IDs to different connections, even if they are inserting into the same table concurrently. You don't even have to wrap the two inserts in a transaction.

So there is no problem at all as long as you're using mysql_insert_id() - it will always work as you would expect it to and won't mix up IDs, and you are completely safe to use the return value from mysql_insert_id as a the foreign key in a record related to the one you have just inserted.

http://dev.mysql.com/doc/refman/5.0/en/mysql-insert-id.html

Upvotes: 2

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