MySQL/SQL: Group by date only on a Datetime column

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.myd         


        

Answer 1

SELECT SUM(No), HOUR(dateofissue) 
FROM tablename 
WHERE dateofissue>='2011-07-30' 
GROUP BY HOUR(dateofissue)

It will give the hour by sum from a particular day!