SQL – NULL Values
Table Of Contents:
- What Are NULL Values?
- Syntax Of NULL Values.
- Examples Of Null Values.
(1) What Are NULL Values ?
- Sometimes users don’t enter every asked value in the input form.
- If a column doesn’t have any value in it there will be NULL inside it.
- Database replaces the empty values with ‘NULL’.
- A field with a NULL value is one that has been left blank during record creation!
(2) Syntax Of NULL Values ?
Syntax:
NULLSELECT column_names
FROM table_name
WHERE column_name IS NULL;SELECT column_names
FROM table_name
WHERE column_name IS NOT NULL;Note:
- NULL values are identified with the “NULL” keyword.
(3) Examples Of NULL Values ?
Demo Data:
Example-1:
SELECT CustomerName, ContactName, Address
FROM Customers
WHERE Address IS NULL;
Example-2:
SELECT CustomerName, ContactName, Address
FROM Customers
WHERE Address IS NOT NULL;