Progress
SQL-92
Guide and Reference


COALESCE Function

Specifies a series of expressions, and returns the first expression whose value is not null. If all the expressions evaluate as null, COALESCE returns a null value.

SYNTAX

COALESCE ( expression1, expression2 [... ] ) 

NOTE: The COALESCE syntax is shorthand notation for a common case that can also be represented in a CASE expression. The following two formulations are equivalent:

COALESCE ( expression1 , expression2 , expression3 ) 

CASE
    WHEN expression1 IS NOT NULL THEN expression1 
    WHEN expression2 IS NOT NULL THEN expression2
    ELSE expression3 
END 

EXAMPLE

This example illustrates the COALESCE function:

SELECT COALESCE (end_date, start_date) from job_hist; 

NOTES

COMPATIBILITY

SQL-92 Compatible


Copyright © 2004 Progress Software Corporation
www.progress.com
Voice: (781) 280-4000
Fax: (781) 280-4095