Retrieves the ID generated for an AUTO_INCREMENT column by the previous INSERT query.
The MySQL connection. If the link identifier is not specified, the last link opened by mysql_connect() is assumed. If no such link is found, it will try to create one as if mysql_connect() was called with no arguments. If by chance no connection is found or established, an E_WARNING level warning is generated.
The ID generated for an AUTO_INCREMENT column by the previous INSERT query on success, 0 if the previous query does not generate an AUTO_INCREMENT value, or FALSE if no MySQL connection was established.
Example 1. mysql_insert_id() example
mysql_insert_id() converts the return type of the native MySQL C API function mysql_insert_id() to a type of long (named int in PHP). If your AUTO_INCREMENT column has a column type of BIGINT, the value returned by mysql_insert_id() will be incorrect. Instead, use the internal MySQL SQL function LAST_INSERT_ID() in an SQL query.
Note: Because mysql_insert_id() acts on the last performed query, be sure to call mysql_insert_id() immediately after the query that generates the value.
Note: The value of the MySQL SQL function LAST_INSERT_ID() always contains the most recently generated AUTO_INCREMENT value, and is not reset between queries.