How do I use "group by" with three columns of data?
My query currently is:

    SELECT x, MAX(z) AS mz, y FROM my_table GROUP BY x

The columns x and mz are returned as expected, but the last column, y, does not match up with the other two. In other words, I want the "y" column to match the mz column just like the x column currently does. How do I pull that off?
How do I use "group by" with three columns of data?
===

My query currently is:

    SELECT x, MAX(z) AS mz, y FROM my_table GROUP BY x

The columns x and mz are returned as expected, but the last column, y, does not match up with the other two. In other words, I want the "y" column to match the mz column just like the x column currently does. How do I pull that off?