getting mysql_insert_id() while using ON DUPLICATE KEY UPDATE with PHP

Question

I've found a few answers for this using mySQL alone, but I was hoping someone could show me a way to get the ID of the last inserted or updated row of a mysql DB when using PHP to handle the inserts/updates.

Currently I have something like this, where column3 is a unique key, and there's also an id column that's an autoincremented primary key:

$query ="INSERT INTO TABLE (column1, column2, column3) VALUES (value1, value2, value3) ON DUPLICATE KEY UPDATE SET column1=value1, column2=value2, column3=value3";
mysql_query($query);

$my_id = mysql_insert_id();

$my_id is correct on INSERT, but incorrect when it's updating a row (ON DUPLICATE KEY UPDATE).

I have seen several posts with people advising that you use something like

INSERT INTO table (a) VALUES (0) ON DUPLICATE KEY UPDATE id=LAST_INSERT_ID(id) 

to get a valid ID value when the ON DUPLICATE KEY is invoked-- but will this return that valid ID to the PHP mysql_insert_id() function?

Answer 1

Here's the answer, as suggested by Alexandre:

when you use the id=LAST_INSERT_ID(id) it sets the value of mysql_insert_id = the updated ID-- so your final code should look like:

<?
    $query = mysql_query("
        INSERT INTO table (column1, column2, column3) 
        VALUES (value1, value2, value3) 
        ON DUPLICATE KEY UPDATE
            column1 = value1, 
            column2 = value2, 
            column3 = value3, 
            id=LAST_INSERT_ID(id)
    ");
    $my_id = mysql_insert_id();

This will return the right value for $my_id regardless of update or insert.