Table of contents

SQL Basic
SQL HOME
SQL 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 It

SQL Advanced
SQL Top
SQL 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 Functions
SQL 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 Quiz

Selected Reading
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SQL Constraints

Constraints are used to limit the type of data that can go into a table.

Constraints can be specified when a table is created (with the CREATE TABLE statement) or after the table is created (with the ALTER TABLE statement).

We will focus on the following constraints:

NOT NULL
UNIQUE
PRIMARY KEY
FOREIGN KEY
CHECK
DEFAULT

The next chapters will describe each constraint in details.

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