Using the GROUP BY clause
The GROUP BY clause enables you to establish data groups based on columns. The grouping criterion is defined by the GROUP BY clause, which is followed by the
WHERE
clause in the SQL execution path. Following this execution path, the result set rows are grouped based on like values of grouping columns and the
WHERE
clause restricts the entries in each group.
Note
All columns that are used besides the aggregate functions must be included in the GROUP BY clause. The GROUP BY clause does not support the use of column aliases; you must use the actual column names. The GROUP BY columns may or may not appear in the
SELECT
list. The GROUP BY clause can only be used with aggregate functions such as
SUM
,
AVG
,
COUNT
, ...
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