SQL

sql not null

SELECT column_name FROM table_name 
WHERE column_name IS NOT NULL;

sql from null to not null

ALTER TABLE ime_tabele
ALTER stolpec SET NOT NULL;

find value if not null in sql

SELECT FIRST_NAME , MANAGER_ID 
FROM EMPLOYEES 
WHERE MANAGER_ID IS NOT NULL ;

sql is null

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

sql is not null

SELECT * FROM my_table WHERE my_column IS NOT NULL;

SQL IS NULL and IS NOT NULL

SELECT *
FROM Employee
WHERE email IS NULL;

NOT NULL SQL

By default, a column can hold NULL values.
The NOT NULL constraint enforces a column to NOT accept NULL values.
This enforces a field to always contain a value, which means that you cannot insert a new record, or update a record without adding a value to this field.

Sql NOT NULL in creating a table
CREATE TABLE Persons (
    ID int NOT NULL,
    LastName varchar(255) NOT NULL,
    FirstName varchar(255) NOT NULL,
    Age int
);

SQL IS NULL

SELECT *
FROM Employee
WHERE email IS NOT NULL;

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;"

is not null sql

select c_custkey, c_name, c_address from customer where c_custkey in (select o_orderkey from orders where o_orderkey IS NOT NULL)