SQL IS NULL Function
Quick summary: The SQL IS NULL operator checks whether a value is NULL.
SQL IS NULL Syntax
expression IS NULLSQL
SQL IS NULL Basic examples
SELECT * FROM users WHERE deleted_at IS NULL;SQL
Output:
Non-deleted usersFilters NULL values.
SQL IS NULL Real-world usage
SELECT * FROM orders WHERE shipped_at IS NULL;SQL
Output:
Unshipped ordersTracks pending actions.
SQL IS NULL Edge cases
SELECT NULL = NULL;SQL
Output:
NULLNULL cannot be compared with =.
SQL IS NULL Common mistakes
Using = NULL
NULL comparisons require IS NULL.
Incorrect
WHERE deleted_at = NULLCorrect
WHERE deleted_at IS NULLUse IS NULL or IS NOT NULL.
SQL IS NULL Frequently Asked Questions
What does IS NULL do in SQL?
Checks if a value is NULL.
Use case of IS NULL?
Filtering missing data.
Syntax?
column IS NULL.
Common mistake?
Using = NULL instead.
Opposite operator?
IS NOT NULL.
Used with WHERE?
Yes.
Performance?
Depends on indexes.
Handles NULL logic?
Yes.
Used in joins?
Yes.
Alternative?
COALESCE.
Used in data cleaning?
Yes.
Best practice?
Always use IS NULL syntax.