COMPUTE Clause
Generates totals that appear as additional summary columns at the end of the result set. When used with BY, the COMPUTE clause generates control-breaks and subtotals in the result set. You can specify COMPUTE BY and COMPUTE in the same query.
Syntax
[ COMPUTE
{ { AVG | COUNT | MAX | MIN | STDEV | STDEVP
| VAR | VARP | SUM }
( expression ) } [ ,...n ]
[ BY expression [ ,...n ] ]
]
Arguments
AVG | COUNT | MAX | MIN | STDEV | STDEVP | VAR | VARP | SUM
Specifies the aggregation to be performed. These row aggregate functions are used with the COMPUTE clause.
| Row aggregate function | Result |
|---|---|
| AVG | Average of the values in the numeric expression |
| COUNT | Number of selected rows |
| MAX | Highest value in the expression |
| MIN | Lowest value in the expression |
| STDEV | Statistical standard deviation for all values in the expression |
| STDEVP | Statistical standard deviation for the population for all values in the expression |
| SUM | Total of the values in the numeric expression |
| VAR | Statistical variance for all values in the expression |
| VARP | Statistical variance for the population for all values in the expression |
There is no equivalent to COUNT(*). To find the summary information produced by GROUP BY and COUNT(*), use a COMPUTE clause without BY.
These functions ignore null values.
The DISTINCT keyword is not allowed with row aggregate functions when they are specified with the COMPUTE clause.
When you add or average integer data, SQL Server treats the result as an int value, even if the data type of the column is smallint or tinyint. For more information about the return types of added or average data, see SUM and AVG.
Note To reduce the possibility of overflow errors in ODBC and DB-Library programs, make all variable declarations for the results of averages or sums the data type int.
( expression )
An expression, such as the name of a column on which the calculation is performed. expression must appear in the select list and must be specified exactly the same as one of the expressions in the select list. A column alias specified in the select list cannot be used within expression.
Note ntext, text, or image data types cannot be specified in a COMPUTE or COMPUTE BY clause.
BY expression
Generates control-breaks and subtotals in the result set. expression is an exact copy of an order_by_expression in the associated ORDER BY clause. Typically, this is a column name or column alias. Multiple expressions can be specified. Listing multiple expressions after BY breaks a group into subgroups and applies the aggregate function at each level of grouping.
If you use COMPUTE BY, you must also use an ORDER BY clause. The expressions must be identical to or a subset of those listed after ORDER BY, and must be in the same sequence. For example, if the ORDER BY clause is:
ORDER BY a, b, c
The COMPUTE clause can be any (or all) of these:
COMPUTE BY a, b, c
COMPUTE BY a, b
COMPUTE BY a
Note In a SELECT statement with a COMPUTE clause, the order of columns in the select list overrides the order of the aggregate functions in the COMPUTE clause. ODBC and DB-Library programmers must be aware of this order requirement to put the aggregate function results in the correct place.
You cannot use COMPUTE in a SELECT INTO statement because statements including COMPUTE generate tables and their summary results are not stored in the database. Therefore, any calculations produced by COMPUTE do not appear in the new table created with the SELECT INTO statement.
You cannot use the COMPUTE clause when the SELECT statement is part of a DECLARE CURSOR statement.