Robert Pearl has heeded the call of hosting the T-SQL Tuesday blog party this month. Please click on the #tsql2day image above to learn more about why the topic is “data-presentation”. If you want to read more party-style blog posts then also check out the summary by Adam Machanic called A Year of Tuesdays: T-SQL Tuesday Meta-Roundup.
Who presents the data to your users? There are occasions when the DBA will be asked to write T-SQL for Manipulating Result Sets. Mr. Pearl mentioned having experience with Using Common Table Expressions in the invitation. I had a similar experience with Using GROUP BY with ROLLUP, CUBE, and GROUPING SETS. Who should present data to the users? Although this blog party has T-SQL in the title this post will be more theoretical than practical.
There are always exceptions to any rule but as a general rule I subscribe to the N-Tier / Multi-tier architecting of applications. There are entire books about the benefits but for the sake of a short post I would like to share just two benefits of this architecture for a DBA. If you plan to stay for the soapboxing then please take a minute and look over this diagram by Damon Armstrong on Multi-tier architecture from his post .NET Application Architecture: the Data Access Layer.
Transact-SQL and SQL Server are used to scatter and gather data. CLR and Business Objects are used for control flow logic. Windows Presentation Foundation and Forms/Controls are used for user interface presentation. Each is a great tool for performing their intended task. You have NEVER used a crescent wrench as a hammer right? In the same tongue in cheek tone, you such NEVER use T-SQL to figure out the next user product suggestion and NEVER use T-SQL to display a dollar sign on the right side of a number.
Let us pretend that you inherited a stored procedure that does format the output so that there is a dollar sign displayed on the right side of a number. Who do you suppose would be tasked if the user wanted a different format? (Euros, two decimal places, in millions, negatives in parenthesis) Each of these has the potential to become a major time suck and also cause some wicked stored procedure sprawl. It has happened, it is still happening and will probably continue to happen but hopefully you are better informed for avoiding the problem.
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