Sybase Adaptive Server Anywhere - Page 352

Alphabetical list of functions
334
date-expression The date.
The following statement returns the value 5.
SELECT DOW( ’1998-07-09’ )
♦ SQL/92 Vendor extension.
♦
Sybase Not supported by Adaptive Server Enterprise.
ESTIMATE function [Miscellaneous]
Provides selectivity estimates for the query optimizer, based on specified
parameters.
ESTIMATE ( column-name [ , value [, relation-string ] ] )
column-name The column used in the estimate.
value The value to which the column is compared.
relation-string The comparison operator used for the comparison,
enclosed in single quotes; the default is ’=’.
The following statement returns the number of
emp_id values estimated to be
greater than 200. The precise value depends on the actions you have carried
out on the database.
SELECT DISTINCT ESTIMATE( emp_id, 200, ’>’ )
FROM employee
♦ SQL/92 Vendor extension.
♦
Sybase Not supported in Adaptive Server Enterprise.
"Query Optimization" on page 835 of the book ASA User’s Guide
ESTIMATE_SOURCE function [Miscellaneous]
Provides the source for selectivity estimates used by the query optimizer.
ESTIMATE_SOURCE ( column-name [, value [ , relation-string ] ]
column-name The name of the column that is being investigated.
value The value to which the column is compared.
relation-string The comparison operator used for the comparison,
enclosed in single quotes; the default is ’=’.
Parameters
Examples
Standards and
compatibility
Function
Syntax
Parameters
Examples
Standards and
compatibility
See also
Function
Syntax
Parameters