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Combining Data from Multiple Database Tables

SQL provides the JOIN statement for combining data from multiple tables in a single query result. In this series of articles, we take an in-depth look at the JOIN command.

Further Reading

Mike's Databases Blog

Microsoft SQL Server DEFAULT Constraints

Thursday December 10, 2009
DEFAULT constraints allow you to specify a value that the database will use to populate fields that are left blank in the input source. They're a replacement for the use of NULL values that provide a great way to predefine common data elements.

Read the full article: DEFAULT Constraints in Microsoft SQL Server 2008

Database Normal Forms

Tuesday December 8, 2009
If you've been working with databases for a while, chances are you've heard the term normalization. Perhaps someone's asked you "Is that database normalized?" or "Is that in BCNF?" All too often, the reply is "Uh, yeah." Normalization is often brushed aside as a luxury that only academics have time for. However, knowing the principles of normalization and applying them to your daily database design tasks really isn't all that complicated and it could drastically improve the performance of your DBMS.

In this article, we introduce the concept of normalization and take a brief look at the most common normal forms.

Read the full Database Normalization Basics article for more!

Relationships Between Database Tables

Sunday December 6, 2009
In a recent forum message, DDKitty wrote:

"Can anyone break down how to create relationships with tables? I've read googled, binged and watched demo's on it, but I still don't get it. It seems too complex.

Do you have to have a primary key? It's really confusing and when I go to try to create a relationship, I either get box dialogues that pop up saying something about my field properties or index stuff.

I also have to enforce referential intergrity and cascading updates and deletions and it seems too complex."

Can you help DDKitty? Interested in solutions to the same problem? Join the discussion in the About Databases forum!

Oracle Certified Professional Certification Spotlight

Thursday December 3, 2009
The Oracle Certified Professional credential provides database professionals a chance to prove their mettle when it comes to Oracle database administration or development. Until recently, the Oracle certification program was somewhat confusing and there were a large number of tracks to reaching OCP status. Recent exam/track retirement announcements consolidated these options into two specific programs, the Database Administrator track and the Application Developer track.

Read the full article: Oracle Certified Professional Certification Spotlight
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