Question

When i join 2 tables i am getting an error

select * from picture where id=(SELECT id FROM user where age= 40 ) 

#1242 – Subquery returns more than 1 row

What is the best way to join these 2 large data tables? I want to have all the results

Answer 1

Replace = by IN

select * from picture where id in (select id from user where age = 40) 

Note, this is only “semi-joining” the two tables, i.e. you will only get pictures as results, not a picture-user relation. If you’re actually trying to do the latter, then you’ll have to inner join the two tables:

select * from picture p
join user u on p.id = u.id -- are you sure about this join condition?
where u.age = 40