How to get ID of the last updated row in MySQL?

Solution 1:

I've found an answer to this problem :)

SET @update_id := 0;
UPDATE some_table SET column_name = 'value', id = (SELECT @update_id := id)
WHERE some_other_column = 'blah' LIMIT 1; 
SELECT @update_id;

EDIT by aefxx

This technique can be further expanded to retrieve the ID of every row affected by an update statement:

SET @uids := null;
UPDATE footable
   SET foo = 'bar'
 WHERE fooid > 5
   AND ( SELECT @uids := CONCAT_WS(',', fooid, @uids) );
SELECT @uids;

This will return a string with all the IDs concatenated by a comma.

Solution 2:

Hm, I am surprised that among the answers I do not see the easiest solution.

Suppose, item_id is an integer identity column in items table and you update rows with the following statement:

UPDATE items
SET qwe = 'qwe'
WHERE asd = 'asd';

Then, to know the latest affected row right after the statement, you should slightly update the statement into the following:

UPDATE items
SET qwe = 'qwe',
    item_id=LAST_INSERT_ID(item_id)
WHERE asd = 'asd';
SELECT LAST_INSERT_ID();

If you need to update only really changed row, you would need to add a conditional update of the item_id through the LAST_INSERT_ID checking if the data is going to change in the row.