Aggregate functions perform a calculation on a set of values and return a single value. With the exception of COUNT, aggregate functions ignore null values. Aggregate functions are often used with the GROUP BY clause of the SELECT statement.
Aggregate functions are allowed as expressions only in:
The Transact-SQL programming language provides these aggregate functions:
| AVG | SUM |
| COUNT | STDEV |
| GROUPING | STDEVP |
| MAX | VAR |
| MIN | VARP |