602SQL Documentation Index  
<­NULLIF Function UpFunctions Defined by the SQL Standard CAST Function­>

COALESCE Function (SQL)

COALESCE ( expression {, expression } )

The COALESCE function returns the value of the first expression that is not NULL. If all expressions are NULL, the function returns NULL. Expressions must have compatible types.

Example:

Replace NULL values with a zero constant in the result of an outer join.

SELECT Companies.name,COALESCE(SUM(invoices.price),0)
FROM Companies LEFT OUTER JOIN invoices ON (Companies.cislo=invoices.company)
GROUP BY Companies.name
<­NULLIF Function UpFunctions Defined by the SQL Standard CAST Function­>