sql not equal with null code example

Example 1: sql not equal

<>	Not equal. Note: In some versions of SQL this operator may be written as !=

Example sql query:

1) Selecting groceries where price is not 20
SELECT * FROM Grocery WHERE Price <> 20;

Example 2: 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
);

Example 3: not equal in sql

row <> value