NOT NULL SQL
snippet in sql

Select without null values sql

user5536

SELECT column_names
FROM table_name
WHERE column_name IS NOT NULL;

sql not null

user4077

SELECT column_name FROM table_name 
WHERE column_name IS NOT NULL;

not null constraint

user4865


  CREATE TABLE Persons (
    ID int NOT NULL,
    
  LastName varchar(255) NOT NULL,
    FirstName varchar(255) 
  NOT NULL,
    Age int
);  

how to check if a column is null in sql

user490

SELECT column_name FROM table_name 
WHERE column_name IS NULL;

NOT NULL SQL

user1135

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
);

alter table not null constraint

user5488

ALTER TABLE Persons
MODIFY Age int NOT NULL;