EXPERIENCE_ESTIMATE function [Miscellaneous]

Returns selectivity estimates from the frequency table as a percentage calculated by the query optimizer, based on specified parameters.

Syntax 
EXPERIENCE_ESTIMATE( 
column-name
[, value 
[, relation-string ] ] 
)
Parameters

  • 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. Possible values for this parameter are: '=' , '>' , '<' , '>=' , '<=' , '<>' , '!=' , '!<' , and '!>'. The default is '='.

Returns

REAL

Remarks

If value is NULL then the relation strings = and != are interpreted as the IS NULL and IS NOT NULL conditions, respectively.

See also
Standards and compatibility

  • SQL/2003   Vendor extension.

Example

The following statement returns NULL.

SELECT DISTINCT EXPERIENCE_ESTIMATE( EmployeeID, 200, '>' )
FROM Employees;
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