constraint not null code example

Example 1: sql not null

SELECT column_name FROM table_name 
WHERE column_name IS NOT NULL;

Example 2: how to add not null constraint in sql

ALTER TABLE table_name MODIFY column_name datatype NOT NULL;

Example 3: sql is not null

The reverse of NULL. Tests for values that aren’t empty / NULL
"Tests for empty (NULL) values.
Example: Returns users that haven’t given a contact number.
SELECT * FROM users
WHERE contact_number IS NULL;"

Example 4: not null constraint

ID int(10) NOT NULL;