选择列中具有多个不同值的行

Question

Assuming I have a table like

a | b | c
--+---+--
1 | 1 | 2
1 | 2 | 3
1 | 2 | 2
3 | 2 | 3

I want to select rows, which have a number of different values WITHIN this row. Something like:

select a,b,c from table having size(unique(a,b,c)) = 2

So for the given set of data, this case the query returns:

a | b | c
--+---+--
1 | 1 | 2
1 | 2 | 2
3 | 2 | 3

Is there a mysql-operand for this kind of thing? Obviously I need to use this with more rows and different values as 2.

Answer 1

There is a neat way of doing this, in case of a,b,c are id's of one table. Then you can do a subquery and do an in predicate like this:

select 
    a,b,c, 
    (select count(distinct(*)) from table where id in (a,b,c)) number
from table 
having number = x

Answer 2

select a,b,c from table WHERE a != b AND b != c AND a != c