Question

I have a table called MyTable like so

A    B
101  Dog
209  Cat
209  Cat
209  Dog
193  Cow
193  Dog
101  Dog
193  Dog
193  Cow

And I want to pull out the most common B for each A so it would end up being like this (note that there can be ties)

    A    B
    101  Dog
    209  Cat
    193  Dog
    193  Cow

How could I write sql to do this?

Answer 1

Alternatively, you can use HAVING clause instead of JOIN.

SELECT A, B
FROM table1 o
GROUP BY A, B
HAVING COUNT(*) = 
    (
        SELECT MAX(totalCOunt)
        FROM
        (
            SELECT A, B, COUNT(*) totalCount
            FROM table1
            GROUP BY A,B
        ) x
        WHERE o.A = x.A 
        GROUP BY x.A
    )

SQLFiddle Demo