Table is specified twice, both as a target for 'UPDATE' and as a separate source for data in mysql

Question

I have below query in mysql where I want to check if branch id and year of finance type from branch_master

Answer 1

The correct answer is in this SO post.

The problem with here accepted answer is - as was already mentioned multiple times - creating a full copy of the whole table. This is way far from optimal and the most space complex one. The idea is to materialize the subset of data used for update only, so in your case it would be like this:

UPDATE manager as m1
SET m1.status = 'Y'
WHERE m1.branch_id IN (
    SELECT * FROM(
        SELECT m2.branch_id FROM manager as m2 
        WHERE (m2.branch_id,m2.year) IN (
            SELECT DISTINCT branch_id,year 
            FROM `branch_master` 
            WHERE type = 'finance')
    ) t
)

Basically you just encapsulate your previous source for data query inside of

SELECT * FROM (...) t