MySQL LAST_INSERT_ID() with INSERT INTO tablea SELECT FROM tableb

Question

Is it possible to update the source table with the LAST_INSERT_ID from the target table?

INSERT INTO `target` SELECT `a`, `b` FROM `source`

The target table has an auto increment key id which I would like to store in the source table for further usage.

Would save me a lot of computing power if something like this would be possible :)

Answer 1

Immediately after executing:

INSERT INTO `target` SELECT `a`, `b` FROM `source`

Call an update on the source table as below:

UPDATE `source` 
SET field_name = LAST_INSERT_ID() 
WHERE col_name_x = some_value_or_expression

Change column names and where conditions and then execute it.