MySQL has an AUTO_INCREMENT column attribute which automatically generates a consistent integer value upon a successful (or not) INSERT. Oftentimes, this attribute is set on a column deemed the PRIMARY KEY. Therefore, providing a unique value for the column and ensuring each rows’ individual identity. The LAST_INSERT_ID() function returns the most recently generated value for a column with the AUTO_INCREMENT attribute. Many times, you use this value further in query processing (E.g., link a newly signed-on customers’ information to a joining table of orders, ensure referential integrity between parent and child tables using a FOREIGN KEY and PRIMARY KEY, INSERT into another related one-to-one table, etc…). The PDO PHP library has a like-named class method, lastInsertId(), which provides the same functionality as LAST_INSERT_ID() in a PHP context. In this post, I’ll visit lastInsertId() with a simple example. Continue reading to learn more…