COALESCE
COALESCE returns the first non-null expression among its arguments.
Syntax
COALESCE (expression1, expression2, expression3…)
This is equivalent to:
CASE
WHEN expression1 NOT NULL THEN expression1
WHEN expression2 NOT NULL THEN expression2
ELSE expression3
END
Remarks
TDV Server supports push of the COALESCE functional expression directly to the following data sources to take advantage of any indices that might yield a performance advantage: DB2, MySQL, Netezza, Oracle, SQL Server, Sybase, and Teradata.
Example
SELECT
CAST (COALESCE (hourly_wage * 40 * 52, salary, commission * num_sales) AS money)
FROM wages