Active record last insert ID

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@meovino

$this->db->insert_id() is a simple wrapper to the PHP MySQL classes mysql_insert_id() function. The only difference is that is suppresses any errors that may come from the call by adding the @ in front of it, and it passes the connection id (which is optional). Here is the code I am referring to from the mysql_driver.php CI file:

Code:

/**
* Insert ID
*
* @access public
* @return integer
*/
function insert_id()
{
  return @mysql_insert_id($this->conn_id);
}

However I think its important to note the difference between the PHP function that this wraps and the direct MySQL function of retrieving the last auto-incremented value for the session. An important difference to note is the following:

In the instance when multiple rows are created with a single insert statement LAST_INSERT_ID() (the direct MySQL function) will return the first inserted rows ID, whereas MYSQL_INSERT_ID() (the PHP function the CI wraps up with $this->db->insert_id()) returns the ID from the last row inserted.

See the following documentation references:
http://dev.mysql.com/doc/refman/5.0/en/m...rt-id.html

In the case of a multiple-row INSERT statement, mysql_insert_id() returns the first automatically generated AUTO_INCREMENT value; if no such value is generated, it returns the last explicit value inserted into the AUTO_INCREMENT column.

http://us.php.net/mysql_insert_id

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.

Thanks,
Rob