IS NULL is a SQL condition used to check whether a column contains a NULL value. Because NULL represents an unknown or missing value, SQL requires IS NULL rather than = NULL when checking for missing values.
Identifying missing information is an important part of data-quality analysis. Analysts frequently need to find records where important fields have not been populated.
If some employees do not have a manager assigned, the ManagerID column may contain NULL. IS NULL can identify those employees.
SELECT
EmployeeID,
EmployeeName
FROM Employees
WHERE ManagerID IS NULL;IS NULL is used for data-quality checks, customer data validation, employee analysis, financial reporting, and missing-data investigations.
- IS NULL identifies missing values.
- IS NULL is used inside conditions.
- IS NULL is different from = NULL.
- NULL values can affect calculations and comparisons.
- IS NULL is useful for data-quality analysis.
How do you find NULL values in SQL?
Use the IS NULL condition.
Why can't you normally use = NULL?
NULL represents an unknown value, so SQL uses IS NULL and IS NOT NULL for NULL comparisons.