Group Functions with Non-group Selections in MySQL

Q

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

✍: FYIcenter.com

A

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:

mysql> SELECT COUNT(*), url FROM fyi_links;
ERROR 1140 (42000): Mixing of GROUP columns 
   (MIN(),MAX(),COUNT(),...) with no GROUP columns
   is illegal if there is no GROUP BY clause

In this example, COUNT(*) is a group field and "url" is a non-group field.

⇒ Dividing Query Output into Groups in MySQL

⇐ Using Group Functions in the SELECT Clause in MySQL

⇑ SELECT Query Statements with GROUP BY in MySQL

⇑⇑ MySQL Database Tutorials

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