ISNULL() - Detecting NULL Value

Q

How to detect a NULL value using the ISNULL() function?

✍: FYIcenter.com

A

ISNULL(val) is a MySQL built-in function that returns 1 if the given value is NULL, 0 otherwise. For example:

SELECT ISNULL(1+1);
  -- +-------------+
  -- | ISNULL(1+1) |
  -- +-------------+
  -- |           0 |
  -- +-------------+

SELECT ISNULL(1/0);
  -- +-------------+
  -- | ISNULL(1/0) |
  -- +-------------+
  -- |           1 |
  -- +-------------+

Reference information of the ISNULL() function:

ISNULL(val): boolean
  Returns TRUE, if and only if the argument is NULL.

Arguments, return value and availability:
  val: Required. The value to be examined.
  boolean: Return value. TRUE, if and only if the argument is NULL.
  Available since MySQL 4.0.

⇒ LEAST() - Finding the Least/Minimum Value

⇐ IS_USED_LOCK() - Checking Lock Owner

⇑ MySQL Functions for Miscellaneous Purposes

⇑⇑ MySQL Function References

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