GROUP BY Clause

GROUP BY divides a query result set into groups of rows that match an expression.

Syntax

GROUP BY expression [ ,... ]

Semantics

expression

is any expression including constants and references to columns in the tables specified in the FROM clause.

Notes

The expression cannot include aggregate functions.
All non-aggregated columns in the SELECT list must be included in the GROUP BY clause.

Examples

SELECT C1, C2

FROM T1

GROUP BY C1, C2;

SELECT C1, AVG(C2)

FROM T1

GROUP BY C1;

SELECT x+y, SUM(z)

FROM foo

GROUP BY x+y;

SELECT x+y, y+z, COUNT(*)

FROM foo

GROUP BY x+y, y+z;

SELECT RTRIM(a) || LTRIM(b), AVG(c), COUNT(c)

FROM foo

GROUP BY RTRIM(a) || LTRIM(b);

Invalid Examples

SELECT C1, C2

FROM T1

GROUP BY C1;