1. SELECT 
    2.   CAST(sum(number)/count(number) as UNSIGNED) as average, 
    3.   date 
    4. FROM stats 
    5. WHERE * 
    6. GROUP BY date

    the valid types for a CAST in MySQL are as follows

    • BINARY[(N)]
    • CHAR[(N)]
    • DATE
    • DATETIME
    • DECIMAL[(M[,D])]
    • SIGNED [INTEGER]
    • TIME
    • UNSIGNED [INTEGER]