MySQL query count multiple values

Question

Consider the following DB table:

c     p
=========
1     'a'
1     'b'
2     'a'
2     'c'

Now, my goal is to retrieve a list of numbers c, for which holds that each number in this list has at least a record with p='a' AND p='b'.

In the example table above, that would be c=1.

Now my question is, how do I accomplish this using one MySQL query?

D'Arcy Rittich · Accepted Answer · 2010-04-13 18:44:57Z

2

select t1.c
from MyTable t1
inner join MyTable t2 on t1.c = t2.c
where t1.p = 'a' and t2.p = 'b'

Update:

select c
from MyTable 
where p in ('a', 'b', 'c', 'd')
group by c
having count(distinct p) = 4

answered Apr 13, 2010 at 18:24

D'Arcy Rittich

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1 Comment

Now, what if the question was p='A' and p='B' AND p='C'. Or even better, p in any of ['A','B','C',...] ?

Larry Lustig · Accepted Answer · 2010-04-13 18:25:26Z

1

There are different ways to attack the problem depending on the rules your data follows if any. Without knowing more about your problem, I would do:

SELECT t1.c FROM table t1 INNER JOIN table t2
  ON t1.c = t2.c
  WHERE t1.p = 'a' AND t2.p = 'b'

answered Apr 13, 2010 at 18:25

Larry Lustig

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