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SQL NULL Value Explained: How to Use IS NULL & IS NOT NULL

Reading time 1 min
Published Aug 9, 2017
Updated Oct 11, 2019

SQL NULL Values: Main Tips

  • This value defines lost data.
  • Tables already contain NULL values.
  • NULL is handled not like other values.

SQL Working with NULL Values

Below there is a table called "People":

ID Last_Name First_Name Address City
1 Bob Bola Nesdan
2 Bill Bove Ergan 13 Nesdan
3 Benny Bari Nesdanger

Hypothetically the "Adress" column is optional. Then when you write a data record without a value assigned it will receive NULL.

Testing is unavailable using default operators, that's why we use IS NULL/IS NOT NULL.

Theory is great, but we recommend digging deeper!

IS NULL: Example

To select NULL data records we use IS NULL operator:

Example
SELECT col_names
FROM tbl_name
WHERE col_name IS NULL;
Example
SELECT Name, Unit 
FROM Products 
WHERE Unit_On_Order IS NULL;

IS NOT NULL: Example

To select data records with no NULL values we use IS NOT NULL operator:

Example
SELECT col_names
FROM tbl_name
WHERE col_name IS NOT NULL;
Example
SELECT Name, Price 
FROM Products 
WHERE Unit_On_Order IS NOT NULL;