splitted subquery and virtual table
I have 3 tables Tag, Software and Software_Tag which make many-to-many relationship between two first.
I wish to split the subquery out on two parts (because i can not do in in one in mysql):
(SELECT softwares_id FROM Software_Tag GROUP BY softwares_id HAVING COUNT(*) >=2) as my
DELETE FROM Software_Tag WHERE tags_id=1 AND softwares_id IN (my)
Here i try use virtual table named 'my' to put it to second query. How could i do it?
now it gets en exception like check your 开发者_运维问答sql server.
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You could just do it as:
DELETE FROM Software_Tag WHERE tags_id=1 AND softwares_id IN
(SELECT softwares_id FROM Software_Tag GROUP BY softwares_id HAVING COUNT(*) >=2)
This should work in MySQL.
Edit .. try this
DELETE ST1
FROM Software_Tag ST1
JOIN (SELECT softwares_id FROM Software_Tag GROUP BY softwares_id HAVING COUNT(*) >=2) ST2 on ST1.softwares_id=ST2.softwares_id
where ST1.tags_id=1
To use temporary tables, you need to do it like this:
DROP TABLE IF EXISTS my_tmp;
CREATE TEMPORARY TABLE my_tmp SELECT softwares_id
FROM Software_Tag GROUP BY softwares_id
HAVING COUNT(*) >=2;
DELETE FROM Software_Tag
WHERE tags_id=1
AND softwares_id IN (SELECT softwares_id FROM my_tmp);
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