How to get the last updated row using a single query - mysql

Question

I searched enough before posting it.
My table structure:
aid | bid | cid | did |
Where aid, bid together are the primary keys.
When I update the value of cid using a where clause for aid, bid I also want to get the did value of the updated row.
Something like this:
$this->db->set('cid', 1, FALSE)
->where(array(
'aid' => $a_id,
'bid' => $b_id
))
->update('my_table')
->select('did');
The above query says:
Fatal error: Call to a member function select() on a non-object in...
I tried this:
How to get ID of the last updated row in MySQL?
Which is like 3 queries.

Answer 1

I'd suggest fetching the values you're about to update, store their IDs in an array, and run an UPDATE with a WHERE id IN (1, 2, ...).
What you're trying to do is not supported by MySQL. You'll need to run at least 2 queries, and since you're fetching the values the first time and already know what values you're updating, then you can also recreate the new row and it's values without using a query after UPDATE.
In your given example:
$this->db->set('cid', 1, FALSE)
->where(array(
'aid' => $a_id,
'bid' => $b_id
))
->update('my_table')
->select('did');
set(), where() and also select() returns an object that builds on the query. However update() return a value which is the results and doesn't have a function called select() and not set() and where() for that matter.