Difference between "HAVING ... GROUP BY" and "GROUP BY ... HAVING"

Question

I have got the table MYTABLE with 2 columns: A and B

I have got the following pieces of the code:

SELECT MYTABLE.A FROM MYTABLE 
    HAVING SUM(MYTABLE.B) > 100
    GROUP BY MYTABLE.A

and

SELECT MYTABLE.A FROM MYTABLE 
    GROUP BY MYTABLE.A
    HAVING SUM(MYTABLE.B) > 100

Is it the same? Is it possible that these 2 codes will return diffrent sets of results?

Thank you in advance

Answer 1

As documented, there is no difference. People are just used to seeing HAVING after GROUP BY.

http://docs.oracle.com/cd/B28359_01/server.111/b28286/statements_10002.htm#SQLRF20040

Specify GROUP BY and HAVING after the where_clause and hierarchical_query_clause. If you specify both GROUP BY and HAVING, then they can appear in either order.

http://sqlfiddle.com/#!4/66e33/1

Answer 2

I originally wrote:

I am not sure your 1st query is valid. As far as I know, HAVING should always come after GROUP BY.

I was corrected by David Aldridge, the Oracle docs state that the order does not matter. Although I don't recommend using HAVING before GROUP for readability reasons (and to prevent confusion with a WHERE clause), it is technically correct. So that makes the answer to your question 'yes, it's the same'.