I have a table which has product quantity column and the database has multiple entries in a single month.
Date format is (YYYY-MM-DD)
Use the following query and it will return the result that you want.
' date field ' is the name of the column where date is inserted and Tablename is the name of the Table.
SELECT MONTH(date field) as month , YEAR(date field) as year , SUM(quantity) as quantity FROM Tablename GROUP BY MONTH( date field )