Reference Guide > TDV Support for SQL Functions > Conditional Functions > ISNULL
 
ISNULL
The ISNULL function returns the first value in the specified expressions that is not NULL; otherwise, it returns NULL. ISNULL is equivalent to the COALESCE function except that it takes only two arguments.
Syntax
ISNULL (expression1, expression2)
Remarks
ISNULL (expression1, expression2) is equivalent to this CASE statement:
CASE WHEN expression1 IS NOT NULL THEN expression1
WHEN expression2 IS NOT NULL THEN expression2
ELSE NULL END
 
The following table lists the data types of the input arguments for ISNULL.
Data Type of expression
Output Type
BINARY, DATE, DECIMAL, FLOAT, INTEGER, INTERVAL_YEAR, INTERVAL_DAY, NULL, STRING, TIME, TIMESTAMP, XML
Follows the ANSI SQL rules for data type precedence.
Example
SELECT ProductID, ISNULL (SalePrice, UnitPrice) “Best Price”
FROM /shared/examples/ds_orders/products products