Adding a constant value column in the group by clause

Question

Netezza sql is giving error on this query:Cause: Invalid column name 'dummy'.

 select col1,col2, '' as dummy, max(col3) from table1  group by col1,col2,dummy

If i remove the dummy from the group by clause, it works fine. But as per sql syntax, I am supposed to include all non aggregate columns in group by.

Answer 1

why do you need it in your group by, you can use an aggregate function and its result would always be right because the value is constant for example:

select col1,col2, min(' ') as dummy, max(col3) from table1  group by col1,col2

Answer 2

It's due to the order of operations...

FROM JOIN WHERE GROUP BY ... SELECT

When using group by, only the fields remaining from the previous step are available. Since you are not declaring your "Dummy" column until the Select statement the group by doesn't know it exists and therefore doesn't need to account for it.

Answer 3

"dummy" is a static column (not in the table), so it does not need to be in the group by because it is an external column.

SELECT col1,
       col2,
       cast(5 as int) AS [dummy],
       max(col3)
FROM test_1
GROUP BY col1,
         col2,
         col3,
        'dummy'

The code produces an outer reference error # 164.

Take a look at these links
http://www.sql-server-helper.com/error-messages/msg-164.aspx

http://www.sql-server-helper.com/error-messages/msg-1-500.aspx