SQL Tutorial SQL Advanced SQL Database SQL References

SQL Server ISNUMERIC() Function



The SQL Server (Transact-SQL) ISNUMERIC() function is used to test whether an expression is a valid numeric type. The function returns 1 if the expression is a valid numeric type, else returns 0.

Syntax

ISNUMERIC(expression)

Parameters

expression Required. Specify the value to test for valid numeric type.

Return Value

Returns 1 if the expression is a valid numeric type. Returns 0 otherwise.

Example 1:

The example below shows the usage of ISNUMERIC() function.

SELECT ISNUMERIC('Paris');
Result: 0

SELECT ISNUMERIC(NULL);
Result: 0

SELECT ISNUMERIC(0);
Result: 1

SELECT ISNUMERIC(10);
Result: 1

SELECT ISNUMERIC(10.25);
Result: 1

SELECT ISNUMERIC('10.25');
Result: 1

Example 2:

Consider a database table called Product with the following records:

ProductNamePriceStockQuantityOrderQuantity
Apple1.0010020
Banana1.2512030
Orange2.15105NULL
Watermelon3.507515

If the OrderQuantity is optional and can contain NULL values. The statement mentioned below will give NULL value.

SELECT *, Price * (StockQuantity + OrderQuantity) AS Inventory  
FROM Product;

This will produce the result as shown below:

ProductNamePriceStockQuantityOrderQuantityInventory
Apple1.0010020120.0
Banana1.2512030187.5
Orange2.15105NULLNULL
Watermelon3.507515315.0

To avoid such situations, the ISNUMERIC() function can be used in conjunction with IIF() function to provide an alternative value to the column if it contains NULL value.

SELECT *, 
Price * (StockQuantity + IIF(ISNUMERIC(OrderQuantity)=0, 0, OrderQuantity)) AS Inventory
FROM Product;

This will produce the result as shown below:

ProductNamePriceStockQuantityOrderQuantityInventory
Apple1.0010020120.0
Banana1.2512030187.5
Orange2.15105NULL225.75
Watermelon3.507515315.0

❮ SQL Server Functions