Question

I have a table named status_t:

**id** **page** **status** **locked**_by
  1      0        2          0
  1      1        2          0
  1      2        2          0
  2      0        0          0
  2      1        2          0
  2      2        2          0

primary key is ( id, page) .

In the above example I would like to update all the
rows that all pages have status = 2.

i.e. the query should update all the rows with id = 1 to status 3. So the table will become

**id** **page** **status** **locked**_by
  1      0        3          1
  1      1        3          1
  1      2        3          1
  2      0        0          0
  2      1        2          0
  2      2        2          0

I have tried:

SELECT * FROM  status_t AS t
 WHERE id IN   
 (SELECT id FROM status WHERE status = 0) LIMIT 10

the above query fetches the rows to be updated but I cannot do that:

UPDATE status_t as S1 WHERE id IN 
(SELECT id FROM status_t WHERE status = 2) 
SET S1.status = 3, S1.locked_by = 1

EDIT:

THE ABOVE TABLE IS JUST AN EXAMPLE.

I do not want to update WHERE id = 1 . I just want to update rows no matter the id
that have status = 2 for the same id.
In the above example if the row with key (2, 2) had status = 2 then it should be updated.

Answer 1

This should work:

update status_t t
join (
    select distinct id from status_t s
    where status=2 and not exists (
        select 1 from status_t ss
        where s.id=ss.id and s.status <> ss.status
    )
) i on i.id = t.id
set t.status = 3

The inner query selects IDs where all values of status are set to 2. It achieves this result by checking that tere are no rows with the same ID and a different status.

Here is a demo on sqlfiddle.