SQL NULL VALUES - IS NULL

NULL Values

NULL value is an unknown and missing value. You cannot define a value for NULLs.

Note NULL does not mean Zero or space.

As NULL is a missing unknown value, you cannot compare 2 NULL values.

IS NULL

To check if a particular column has NULL Value, you have to use the ‘IS NULL ’ operator.

For Example, suppose you need to get the products which does not have a defined color or which contains a missing unknown value, then you can use IS NULL operator –

Example

SELECT ProductID, Name, Color
FROM Production.Product
WHERE Color IS NULL;

IS NOT NULL

Similarly, we can also test if a particular field does not contain NULL values using ‘NOT NULL’ operator.

Example

SELECT ProductID, Name, Color
FROM Production.Product
WHERE Color IS NOT NULL;

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