[!INCLUDE sql-asdb-asdbmi-asa-pdw-fabricse-fabricdw-fabricsqldb]

Replaces NULL with the specified replacement value.

:::image type="icon" source="../../includes/media/topic-link-icon.svg" border="false"::: Transact-SQL syntax conventions

ISNULL ( check_expression , replacement_value )

The expression to be checked for NULL. check_expression can be of any type.

The expression to be returned if check_expression is NULL. replacement_value must be of a type that is implicitly convertible to the type of check_expression.

Returns the same type as check_expression. If a literal NULL is provided as check_expression, ISNULL returns the data type of the replacement_value. If a literal NULL is provided as check_expression and no replacement_value is provided, ISNULL returns an int.

The value of check_expression is returned if it's not NULL. Otherwise, replacement_value is returned after it's implicitly converted to the type of check_expression, if the types are different. replacement_value can be truncated if replacement_value is longer than check_expression.

[!INCLUDE article-uses-adventureworks]

The following example finds the average of the weight of all products. It substitutes the value 50 for all NULL entries in the Weight column of the Product table.

USE AdventureWorks2022;
GO
SELECT AVG(ISNULL(Weight, 50))
FROM Production.Product;
GO

[!INCLUDE ssResult]

59.79

The following example selects the description, discount percentage, minimum quantity, and maximum quantity for all special offers in [!INCLUDE sssampledbobject-md]. If the maximum quantity for a particular special offer is NULL, the MaxQty shown in the result set is 0.00.

USE AdventureWorks2022;
GO
SELECT Description, DiscountPct, MinQty, ISNULL(MaxQty, 0.00) AS 'Max Quantity'
FROM Sales.SpecialOffer;
GO

[!INCLUDE ssResult]

The following example uses ISNULL to replace a NULL value for Color, with the string None.

USE AdventureWorks2022;
GO
SELECT ProductID,
    Name,
    ProductNumber,
    ISNULL(Color, 'None') AS Color
FROM Production.Product;

Here's a partial result set.

Don't use ISNULL to find NULL values. Use IS NULL instead. The following example finds all products that have NULL in the weight column. Note the space between IS and NULL.

USE AdventureWorks2022;
GO
SELECT Name, Weight
FROM Production.Product
WHERE Weight IS NULL;
GO

The following example finds the average of the weight of all products in a sample table. It substitutes the value 50 for all NULL entries in the Weight column of the Product table.

-- Uses AdventureWorksDW

SELECT AVG(ISNULL(Weight, 50))
FROM dbo.DimProduct;

[!INCLUDE ssResult]

52.88

The following example uses ISNULL to test for NULL values in the column MinPaymentAmount and display the value 0.00 for those rows.

-- Uses AdventureWorks

SELECT ResellerName,
       ISNULL(MinPaymentAmount,0) AS MinimumPayment
FROM dbo.DimReseller
ORDER BY ResellerName;

Here's a partial result set.

The following example finds all products that have NULL in the Weight column. Note the space between IS and NULL.

-- Uses AdventureWorksDW

SELECT EnglishProductName, Weight
FROM dbo.DimProduct
WHERE Weight IS NULL;

• Expressions (Transact-SQL)
• IS NULL (Transact-SQL)
• System Functions by category for Transact-SQL
• WHERE (Transact-SQL)
• COALESCE (Transact-SQL)