SQL
- Introduction To SQL
- SQL Syntax
- SQL SELECT Statement
- SQL SELECT DISTINCT Statement
- SQL WHERE Clause
- SQL AND, OR And NOT Operators
- SQL ORDER BY Keyword
- SQL INSERT INTO Statement
- SQL NULL Values
- SQL UPDATE Statement
- SQL DELETE Statement
- SQL TOP, LIMIT, FETCH FIRST Or ROWNUM Clause
- SQL MIN() And MAX() Functions
- SQL COUNT(), AVG() And SUM() Functions
- SQL LIKE Operator
- SQL Wildcards
- SQL IN Operator
- SQL BETWEEN Operator
- SQL Aliases
- SQL Joins
- SQL INNER JOIN Keyword
- SQL LEFT JOIN Keyword
- SQL RIGHT JOIN Keyword
- SQL FULL OUTER JOIN Keyword
- SQL Self Join
- SQL UNION Operator
- SQL GROUP BY Statement
- SQL HAVING Clause
- SQL EXISTS Operator
- SQL ANY And ALL Operators
- SQL SELECT INTO Statement
- SQL INSERT INTO SELECT Statement
- SQL CASE Statement
- SQL NULL Functions
- SQL Stored Procedures For SQL Server
- SQL Comments
- SQL Operators
- SQL CREATE DATABASE Statement
- SQL DROP DATABASE Statement
- SQL BACKUP DATABASE For SQL Server
- SQL CREATE TABLE Statement
- SQL DROP TABLE Statement
- SQL ALTER TABLE Statement
- SQL Constraints
- SQL NOT NULL Constraint
- SQL UNIQUE Constraint
- SQL PRIMARY KEY Constraint
- SQL FOREIGN KEY Constraint
- ALTER TABLE Orders DROP CONSTRAINT FK_PersonOrder;
- SQL DEFAULT Constraint
- SQL CREATE INDEX Statement
- SQL AUTO INCREMENT Field
- SQL Working With Dates
- SQL Views
- SQL Injection
- SQL Hosting
- SQL Data Types For MySQL, SQL Server, And MS Access
SQL NOT NULL Constraint
SQL NOT NULL Constraint
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.
Practice Excercise Practice now
SQL NOT NULL On CREATE TABLE
The following SQL ensures that the "ID", "LastName", and "FirstName" columns will NOT accept NULL values when the "Persons" table is created:
Example
CREATE TABLE Persons (
ID int NOT NULL,
LastName varchar(255) NOT NULL,
FirstName varchar(255) NOT NULL,
Age int
);
ID int NOT NULL,
LastName varchar(255) NOT NULL,
FirstName varchar(255) NOT NULL,
Age int
);
Practice Excercise Practice now
SQL NOT NULL On ALTER TABLE
To create a NOT NULL constraint on the "Age" column when the "Persons" table is already created, use the following SQL:
ALTER TABLE Persons
MODIFY Age int NOT NULL;
MODIFY Age int NOT NULL;
Practice Excercise Practice now
Products
Partner
Copyright © RVR Innovations LLP 2025 | All rights reserved - Mytat.co is the venture of RVR Innovations LLP