Get the new record primary key ID from MySQL insert query?

You need to use the LAST_INSERT_ID() function: http://dev.mysql.com/doc/refman/5.0/en/information-functions.html#function_last-insert-id

Eg:

INSERT INTO table_name (col1, col2,...) VALUES ('val1', 'val2'...);
SELECT LAST_INSERT_ID();

This will get you back the PRIMARY KEY value of the last row that you inserted:

The ID that was generated is maintained in the server on a per-connection basis. This means that the value returned by the function to a given client is the first AUTO_INCREMENT value generated for most recent statement affecting an AUTO_INCREMENT column by that client.

So the value returned by LAST_INSERT_ID() is per user and is unaffected by other queries that might be running on the server from other users.