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SQL Server FAQ - Mixing Group Functions with Non-group Selection Fields

By: FYIcenter.com

(Continued from previous topic...)

Can Group Functions Be Mixed with Non-group Selection Fields?

If a group function is used in the SELECT clause, all other selection fields must be group level fields. Non-group fields can not be mixed with group fields in the SELECT clause. The script below gives you an example of invalid SELECT statements with group and non-group selection fields mixed in a SELECT statement:

SELECT COUNT(*), url FROM fyi_links
GO
Msg 8120, Level 16, State 1, Line 1
Column 'fyi_links.url' is invalid in the select list because
it is not contained in either an aggregate function or the 
GROUP BY clause.

SELECT 2*COUNT(*), 2*counts FROM fyi_links
GO
Msg 8120, Level 16, State 1, Line 1
Column 'fyi_links.counts' is invalid in the select list 
because it is not contained in either an aggregate function
or the GROUP BY clause.

In these examples, COUNT(*) is a group field and "url"/"2*counts" is a non-group field. The error message also tells that "url"/"counts" is not an aggregate function (group function).

(Continued on next topic...)

1. What Is a SELECT Query Statement?
2. How To Create a Testing Table with Test Data?
3. How To Select All Columns of All Rows from a Table with a SELECT statement?
4. How To Select Some Specific Columns from a Table in a Query?
5. How To Select Some Specific Rows from a Table?
6. How To Add More Data to the Testing Table?
7. How To Sort the Query Output with ORDER BY Clauses?
8. Can the Query Output Be Sorted by Multiple Columns?
9. How To Sort Query Output in Descending Order?
10. How To Count Rows with the COUNT(*) Function?
11. Can SELECT Statements Be Used on Views?
12. How To Filter Out Duplications in the Returning Rows?
13. What Are Group Functions in Query Statements?
14. How To Use Group Functions in the SELECT Clause?
15. Can Group Functions Be Mixed with Non-group Selection Fields?
16. How To Divide Query Output into Multiple Groups with the GROUP BY Clause?
17. How To Apply Filtering Criteria at Group Level with The HAVING Clause?
18. How To Count Duplicated Values in a Column?
19. Can Multiple Columns Be Used in GROUP BY?
20. Can Group Functions Be Used in the ORDER BY Clause?