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Posted Tuesday, November 20, 2007 6:55 AM
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I want to know about Database design. If we think about 'DataBase Design', which would trigger first in our mind ?

Pls dont tell 'do a search'. I am expecting some good answers from best experts.


karthik
Post #424073
Posted Tuesday, November 20, 2007 8:45 AM


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First questions that come to mind.

What's the database for?
What's going to be stored in it, for how long and why?
Who's going to be using this and how?



Gail Shaw
Microsoft Certified Master: SQL Server 2008, MVP
SQL In The Wild: Discussions on DB performance with occasional diversions into recoverability

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Post #424166
Posted Saturday, November 24, 2007 2:24 AM
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Hi karthikeyan,
when we think abount DB Design the 1st trigger comes in mind is DDL trigger on database.

Trigger depends on the requirements.
Post #425398
Posted Saturday, November 24, 2007 10:44 AM


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"3rd Normal Form"

Heh... Look it up ;)


--Jeff Moden
"RBAR is pronounced "ree-bar" and is a "Modenism" for "Row-By-Agonizing-Row".

First step towards the paradigm shift of writing Set Based code:
Stop thinking about what you want to do to a row... think, instead, of what you want to do to a column."

(play on words) "Just because you CAN do something in T-SQL, doesn't mean you SHOULDN'T." --22 Aug 2013

Helpful Links:
How to post code problems
How to post performance problems
Post #425442
Posted Sunday, November 25, 2007 11:21 PM
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whcih one should comes to mind ?

3 rd normal form
(or)
What's the database for?
What's going to be stored in it, for how long and why?
Who's going to be using this and how?
(or)
both



karthik
Post #425550
Posted Sunday, November 25, 2007 11:39 PM
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absolutly correct karthikeyan, but beforeDB design we need to analyze do we really need a trigger. If yes the for what purpose we will desing it , trigger may be on table or on database (in Sql 2005 ) so it depends upon the user as well as on developer also.

If suppose DB dev. want to maintain DDL log audit on database then will write a DB trigger.
if want to maintain any table audit will create trigger on tables.


Post #425561
Posted Monday, November 26, 2007 8:52 AM


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Ahbijit,

Karthick doesn't need a "trigger"... what he said was...
I want to know about Database design. If we think about 'DataBase Design', which would trigger first in our mind ?

... and where he said "which would trigger first in our mind?", he meant "What should be the first thing we take into consideration when designing a database?


--Jeff Moden
"RBAR is pronounced "ree-bar" and is a "Modenism" for "Row-By-Agonizing-Row".

First step towards the paradigm shift of writing Set Based code:
Stop thinking about what you want to do to a row... think, instead, of what you want to do to a column."

(play on words) "Just because you CAN do something in T-SQL, doesn't mean you SHOULDN'T." --22 Aug 2013

Helpful Links:
How to post code problems
How to post performance problems
Post #425834
Posted Monday, November 26, 2007 8:57 AM


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3 rd normal form
(or)
What's the database for?
What's going to be stored in it, for how long and why?
Who's going to be using this and how?
(or)
both

Both... you cannot design a database in correct 3rd normal form without knowing the rest "what's going to be stored in it".

The "how long" and "who's going to be using this and how" actually doesn't matter much. Whether it's for a GUI or Batch File processing doesn't matter because it should always be able to do both.

If you're talking a "data mart", then that's something different. Frequently, they are both pre-summarized and somewhat "de-normalized" for performance reasons.


--Jeff Moden
"RBAR is pronounced "ree-bar" and is a "Modenism" for "Row-By-Agonizing-Row".

First step towards the paradigm shift of writing Set Based code:
Stop thinking about what you want to do to a row... think, instead, of what you want to do to a column."

(play on words) "Just because you CAN do something in T-SQL, doesn't mean you SHOULDN'T." --22 Aug 2013

Helpful Links:
How to post code problems
How to post performance problems
Post #425837
Posted Monday, November 26, 2007 11:22 AM


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Jeff Moden (11/26/2007)
3 rd normal form
(or)
What's the database for?
What's going to be stored in it, for how long and why?
Who's going to be using this and how?
(or)
both

Both... you cannot design a database in correct 3rd normal form without knowing the rest "what's going to be stored in it".

The "how long" and "who's going to be using this and how" actually doesn't matter much. Whether it's for a GUI or Batch File processing doesn't matter because it should always be able to do both.

If you're talking a "data mart", then that's something different. Frequently, they are both pre-summarized and somewhat "de-normalized" for performance reasons.


3NF kind of entails that you know what the "database is for". Keep in mind that the single question "what's the DB for" represents a whole (often iterative) process describing in detail what the DB is for. You need to have an idea of the breadth and depth of the data you need to collect (let's call that the "universe"); you then need to organize your universe into items that naturally go together (let's call them "entities"), and then determine how your entities should relate to each other. Then, using 3NF, you then start looking at your ENTITIES, and try to make sure that THEY don't need to be broken up and organized into more granular entities, etc...

This is not a single question anymore, as you can see. It's an intricate process, requiring involvement from both the business, dev and data areas in most cases.


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Post #425920
Posted Monday, November 26, 2007 1:38 PM


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Jeff Moden (11/26/2007)


The "how long" and "who's going to be using this and how" actually doesn't matter much.


I had a reason for writing those, but now I can't remember fully.

Hmmm.... Think it had to do with need for archiving and growth planning (how long). OLTP or decision support (ie, do we need to consider storing pre-computed averages, selective denormalisation, etc)

But those are more advanced concepts in DB design, and one of the biggest mistakes I see is people skipping intermediate steps to get to a final design.ie not bothering to normalise fully.



Gail Shaw
Microsoft Certified Master: SQL Server 2008, MVP
SQL In The Wild: Discussions on DB performance with occasional diversions into recoverability

We walk in the dark places no others will enter
We stand on the bridge and no one may pass

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