INDEX_ESTIMATE function [Miscellaneous]

INDEX_ESTIMATE( column-name [ , value [ , relation-string ] ] )

column-name The column used in the estimate.
value The value to which the column is compared. The default is NULL.
relation-string The comparison operator used for the comparison, enclosed in single quotes. Possible values for this parameter are: '=' , '>' , '<' , '>=' , '<=' , '<>' , '!=' , '!<' , and '!>'. The default is '='.

REAL

This function returns selectivity estimates from the index for the predicate column-name relation-string value. If value is NULL and the relation string is '=', the selectivity is for the predicate column-name IS NULL. If value is NULL and the relation string is '!=' or '<>', the selectivity is for the predicate column-name IS NOT NULL.

SQL/2008 Vendor extension.

The following statement returns the percentage of EmployeeID values estimated to be greater than 200:

SELECT INDEX_ESTIMATE( EmployeeID, 200, '>' )
FROM GROUPO.Employees;

INDEX_ESTIMATE function [Miscellaneous]

Syntax

Parameters

Returns

Remarks

See also

Standards and compatibility

Example