mysql update query with sub query

Question

Can anyone see what is wrong with the below query?

When I run it I get:

#1064 - You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'a where a.CompetitionID = Competition.CompetitionID' at line 8

Update Competition
Set Competition.NumberOfTeams =
(
SELECT count(*) as NumberOfTeams
FROM PicksPoints
where UserCompetitionID is not NULL
group by CompetitionID
) a
where a.CompetitionID =  Competition.CompetitionID

score 187 · Accepted Answer · answered Jul 21 '12 at 01:24

The main issue is that the inner query cannot be related to your where clause on the outer update statement, because the where filter applies first to the table being updated before the inner subquery even executes. The typical way to handle a situation like this is a multi-table update.

Update
  Competition as C
  inner join (
    select CompetitionId, count(*) as NumberOfTeams
    from PicksPoints as p
    where UserCompetitionID is not NULL
    group by CompetitionID
  ) as A on C.CompetitionID = A.CompetitionID
set C.NumberOfTeams = A.NumberOfTeams

Demo: http://www.sqlfiddle.com/#!2/a74f3/1

I had to do something like: UPDATE tableA AS A INNER JOIN tableB AS B ON A.tag = B.tag SET A.tagId = B.id — Henry, Jan 21 '20 at 10:45

score 24 · Answer 2 · answered Sep 04 '13 at 12:37

Thanks, I didn't have the idea of an UPDATE with INNER JOIN.

In the original query, the mistake was to name the subquery, which must return a value and can't therefore be aliased.

UPDATE Competition
SET Competition.NumberOfTeams =
(SELECT count(*) -- no column alias
  FROM PicksPoints
  WHERE UserCompetitionID is not NULL
  -- put the join condition INSIDE the subquery :
  AND CompetitionID =  Competition.CompetitionID
  group by CompetitionID
) -- no table alias

should do the trick for every record of Competition.

To be noticed :

The effect is NOT EXACTLY the same as the query proposed by mellamokb, which won't update Competition records with no corresponding PickPoints.

Since SELECT id, COUNT(*) GROUP BY id will only count for existing values of ids,

whereas a SELECT COUNT(*) will always return a value, being 0 if no records are selected.

This may, or may not, be a problem for you.

0-aware version of mellamokb query would be :

Update Competition as C
LEFT join (
  select CompetitionId, count(*) as NumberOfTeams
  from PicksPoints as p
  where UserCompetitionID is not NULL
  group by CompetitionID
) as A on C.CompetitionID = A.CompetitionID
set C.NumberOfTeams = IFNULL(A.NumberOfTeams, 0)

In other words, if no corresponding PickPoints are found, set Competition.NumberOfTeams to zero.

sun · Answer 3 · 2019-02-05T23:48:04.290

19

For the impatient:

UPDATE target AS t
INNER JOIN (
  SELECT s.id, COUNT(*) AS count
  FROM source_grouped AS s
  -- WHERE s.custom_condition IS (true)
  GROUP BY s.id
) AS aggregate ON aggregate.id = t.id
SET t.count = aggregate.count

That's @mellamokb's answer, as above, reduced to the max.

edited Feb 05 '19 at 23:48

answered Jan 16 '16 at 05:53

sun

991
9
13

score -2 · Answer 4 · answered Jan 08 '21 at 15:59

You can check your eav_attributes table to find the relevant attribute IDs for each image role, such as;

Then you can use those to set whichever role to any other role for all products like so;

UPDATE catalog_product_entity_varchar AS `v` INNER JOIN (SELECT `value`,`entity_id` FROM `catalog_product_entity_varchar` WHERE `attribute_id`=86) AS `j` ON `j`.`entity_id`=`v`.entity_id SET `v`.`value`=j.`value` WHERE `v`.attribute_id = 85 AND `v`.`entity_id`=`j`.`entity_id`

The above will set all your 'base' roles to the 'small' image of the same product.

mysql update query with sub query

4 Answers4

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