ISNUMERIC() Function in SQL Server

Q: What is the use of the ISNUMERIC() function?

The ISNUMERIC() function checks if a value can be interpreted as a numeric type, returning 1 for numeric values and 0 for non-numeric ones. It helps validate data before performing numeric operations.

Q: Why avoid using ISNUMERIC() in SQL?

ISNUMERIC() can return 1 for values that aren't strictly numeric but are convertible, such as currency symbols or scientific notation, leading to false positives in numeric validation.

Q: What can I use instead of ISNUMERIC() in SQL Server?

Instead of ISNUMERIC(), use TRY_CAST() or TRY_CONVERT() for more accurate numeric validation, as they return NULL for conversion failures, avoiding false positives.

Last Updated : 11 Sep, 2024

The ISNUMERIC() function in SQL Server is a critical tool for determining whether a given expression or value can be interpreted as a numeric type.

This function is valuable for data validation and ensuring that values conform to numeric formats before performing calculations or other operations that require numeric inputs.

In this article, We will learn about ISNUMERIC() Functions in SQL Server by understanding various examples in detail.

ISNUMERIC() Function in SQL Server

The ISNUMERIC() function is used to determine whether a given expression or value is numeric.
This function is commonly used in SQL Server to check if a value can be interpreted as a number.
It helps in validating data to ensure that it conforms to numeric formats before performing operations that require numeric inputs.

Features of ISNUMERIC() Function in SQL Server

This function is used to check if the given expression is numeric or not.
This function returns 1 if the given expression is in numerical form.
This function returns 0 if the given expression is not numeric.
This function comes under Advanced Functions.
This function accepts only one parameter namely expression.

Syntax:

ISNUMERIC(expression)

Parameter:

expression: The value or column to be checked for numeric compatibility.

Return Type: It returns 1 if the specified value is numeric form else it returns 0.

Examples of ISNUMERIC() Function in SQL Server

Example 1: Using ISNUMERIC() function and getting the output

SELECT ISNUMERIC(1352);

Output:

Here, 1 is returned as the stated value is numeric.

Example 2: Using ISNUMERIC() function and getting the output

SELECT ISNUMERIC('abd');

Output:

Here, 0 is returned as output as the stated expression is not numeric.

Example 3: Using ISNUMERIC() function and getting the output using a variable

DECLARE @exp INT;
SET @exp = 44;
SELECT ISNUMERIC(@exp);

Output:

Example 4: Using ISNUMERIC() function and getting the output using multiplication operation and a variable as well

DECLARE @exp INT;
SET @exp = 30*7;
SELECT ISNUMERIC(@exp);

Output:

Application: This function is used to test if the stated expression is numeric or not.

Conclusion

The ISNUMERIC() function provides a straightforward method for checking the numeric status of a value in SQL Server. It returns 1 if the expression is numeric and 0 if it is not, facilitating effective data validation and error handling.

FAQs

What is the use of the `ISNUMERIC()` function?

The ISNUMERIC() function checks if a value can be interpreted as a numeric type, returning 1 for numeric values and 0 for non-numeric ones. It helps validate data before performing numeric operations.

Why avoid using `ISNUMERIC()` in SQL?

ISNUMERIC() can return 1 for values that aren’t strictly numeric but are convertible, such as currency symbols or scientific notation, leading to false positives in numeric validation.

What can I use instead of `ISNUMERIC()` in SQL Server?

Instead of ISNUMERIC(), use TRY_CAST() or TRY_CONVERT() for more accurate numeric validation, as they return NULL for conversion failures, avoiding false positives.