Oracle Consulting Oracle Training Oracle Support Development
Home
Catalog
Oracle Books
SQL Server Books
IT Books
Job Interview Books
eBooks
Rampant Horse Books
911 Series
Pedagogue Books

Oracle Software
image
Write for Rampant
Publish with Rampant
Rampant News
Rampant Authors
Rampant Staff
 Phone
 800-766-1884
Oracle News
Oracle Forum
Oracle Tips
Articles by our Authors
Press Releases
SQL Server Books
image
image

Oracle 11g Books

Oracle tuning

Oracle training

Oracle support

Remote Oracle

STATSPACK Viewer

Privacy Policy

 

   
  SQL Server Tips by Burleson

Foreign Key

A foreign key enforces referential integrity by requiring that the values from a column either exist in a referenced table or are NULL. Relationships between tables are established by defining primary keys or unique keys and referencing them with foreign keys.

Example: To create a one to many relationship between Table1 and Table2. Table1_ID is the name of the column that is the primary key from Table1; Table2_f is the foreign key from Table2 that will relate both tables.

ALTER TABLE dbo.Table2 ADD CONSTRAINT
FK_Table2_Table1 FOREIGN KEY
(
Table2_f
) REFERENCES dbo.Table1
(
Table1_ID
)


For a one to one relationship, both related columns must be primary keys. In this example, Table2_f should be a primary key or unique. A column can be a primary key and a foreign key simultaneously.


The above book excerpt is from:

Super SQL Server Systems
Turbocharge Database Performance with C++ External Procedures

ISBN: 0-9761573-2-2
Joseph Gama, P. J. Naughter

 http://www.rampant-books.com/book_2005_2_sql_server_external_procedures.htm  

Linux Oracle commands syntax poster

ION Oracle tuning software

Oracle data dictionary reference poster



Oracle Forum

BC Oracle consulting support training

BC remote Oracle DBA   

 

   

 Copyright © 1996 -2016 by Burleson. All rights reserved.


Oracle® is the registered trademark of Oracle Corporation. SQL Server® is the registered trademark of Microsoft Corporation. 
Many of the designations used by computer vendors to distinguish their products are claimed as Trademarks
 

Hit Counter