SQL Basic
SQL HOMESQL Intro
SQL Syntax
SQL Select
SQL Distinct
SQL Where
SQL And & Or
SQL Order By
SQL Insert
SQL Update
SQL Delete
SQL Demo
SQL Try ItSQL Advanced
SQL TopSQL Like
SQL Wildcards
SQL In
SQL Between
SQL Alias
SQL Joins
SQL Inner Join
SQL Left Join
SQL Right Join
SQL Full Join
SQL Union
SQL Select Into
SQL Create DB
SQL Create Table
SQL Constraints
SQL Not Null
SQL Unique
SQL Primary Key
SQL Foreign Key
SQL Check
SQL Default
SQL Create Index
SQL Drop
SQL Alter
SQL Increment
SQL Views
SQL Dates
SQL Nulls
SQL isnull()
SQL Data Types
SQL Functions
SQL FunctionsSQL avg()
SQL count()
SQL first()
SQL last()
SQL max()
SQL min()
SQL sum()
SQL Group By
SQL Having
SQL ucase()
SQL lcase()
SQL mid()
SQL len()
SQL round()
SQL now()
SQL format()
SQL Quick Ref
SQL Hosting
SQL Summary
SQL Quiz
SQL QuizSQL NOT NULL Constraint
By default, a table column can hold NULL values.
SQL NOT NULL Constraint
The NOT NULL constraint enforces a column to NOT accept NULL values.
The NOT NULL constraint enforces a field to always contain a value. This means that you cannot insert a new record, or update a record without adding a value to this field.
The following SQL enforces the "P_Id" column and the "LastName" column to not accept NULL values:
(
P_Id int NOT NULL,
LastName varchar(255) NOT NULL,
FirstName varchar(255),
Address varchar(255),
City varchar(255)
)
W3Schools' Online Certification
The perfect solution for professionals who need to balance work, family, and career building.
More than 10 000 certificates already issued!
The HTML Certificate documents your knowledge of HTML.
The CSS Certificate documents your knowledge of advanced CSS.
The JavaScript Certificate documents your knowledge of JavaScript and HTML DOM.
The jQuery Certificate documents your knowledge of jQuery.
The XML Certificate documents your knowledge of XML, XML DOM and XSLT.
The ASP Certificate documents your knowledge of ASP, SQL, and ADO.
The PHP Certificate documents your knowledge of PHP and SQL (MySQL).
| WEB HOSTING |
|---|
| Best Web Hosting |
| PHP MySQL Hosting |
| Best Hosting Coupons |
| UK Reseller Hosting |
| Cloud Hosting |
| Top Web Hosting |
| $7.95/mo SEO Hosting |
| Premium Website Design |
| WEB BUILDING |
|---|
| Download XML Editor |
| FREE Website BUILDER |
| Free Website Templates Free CSS Templates |
| Make Your Own Website |
| W3SCHOOLS EXAMS |
|---|
|
Get Certified in: HTML, CSS, JavaScript, XML, PHP, and ASP |
| W3SCHOOLS BOOKS |
|---|
|
New Books: HTML, CSS JavaScript, and Ajax |
| STATISTICS |
|---|
|
Browser Statistics Browser OS Browser Display |
| SHARE THIS PAGE |
|---|
Tutorials, references, and examples are constantly reviewed to avoid errors, but we cannot warrant full correctness of all content.
While using this site, you agree to have read and accepted our terms of use and privacy policy.
Copyright 1999-2012 by Refsnes Data. All Rights Reserved.