Question

Having a table with a column like: mydate DATETIME …

I have a query such as:

SELECT SUM(foo), mydate FROM a_table GROUP BY a_table.mydate; 

This will group by the full datetime, including hours and minutes. I wish to make the group by, only by the date YYYY/MM/DD not by the YYYY/MM/DD/HH/mm.

How to do this?

Answer 1

Cast the datetime to a date, then GROUP BY using this syntax:

SELECT SUM(foo), DATE(mydate) FROM a_table GROUP BY DATE(a_table.mydate); 

Or you can GROUP BY the alias as @orlandu63 suggested:

SELECT SUM(foo), DATE(mydate) DateOnly FROM a_table GROUP BY DateOnly; 

Though I don’t think it’ll make any difference to performance, it is a little clearer.