如果字段数低于SQL查询中每行的数字，如何获取行

Question

Let me try to explain my problem: I have two tables

 Table A
    |user|type|
    |----|----|
    |A   |1   |
    |B   |2   |
    |A   |1   |
    |A   |1   |

and

 Table B   
    |type|value|
    |----|-----|
    |1   |2    |
    |2   |1    |

I want to get rows if count of each user in table A is less or equal than proper type value from table B.

So result for this example should be:

user|user count
----|----------
B   |1 

Answer 1

Nikola, you did not say if the user with multiple rows in A has always the same type. Assuming is has:

select user, cnt as 'user count'
from (
select a.user, b.value, count(*) as cnt
from a
 join b on a.type=b.type
group by a.user, b.value
having count(*) <= b.value
) as q

See SQLFiddle .