Problem to write Special Function

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Problem to write Special Function

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Jeff Moden SSC Guru Points: 1004664 More actions · Answer 1

Golden_Behzad (3/7/2012)
For Create Function For SequenceID YouCan Use This Function But This Function Is Very Bad Performance and If multi user call this in some time generate duplicate id .
to generate almost sequence id i can use guid as binary in last code to generate unique id but not sequence

That's what I've been trying to tell you. Creating your own sequence function will be nothing but a performance mess and possibly cause duplicate ID's. The auto-numbering of the sequential numbers of an IDENTITY type of column are absolutely bullet-proof and incredibly fast. You'll need to add an extra column to hold the result of your function, anyway, so why not use what's built in?

--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.

Change is inevitable... Change for the better is not.

Helpful Links:
How to post code problems
How to Post Performance Problems
Create a Tally Function (fnTally)

Golden_Behzad SSC Journeyman Points: 79 More actions · Answer 2

Golden_Behzad

SSC Journeyman

Points: 79

March 8, 2012 at 7:59 am

#1456543

how to use?

Sean Lange SSC Guru Points: 286609 More actions · Answer 3

Golden_Behzad (3/8/2012)
how to use?

As explained previously in this thread, it is an IDENTITY.

http://msdn.microsoft.com/en-us/library/ms186775.aspx

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Jeff Moden SSC Guru Points: 1004664 More actions · Answer 4

Golden_Behzad (3/8/2012)
how to use?

Please lookup IDENTITY column in Books Online. It's nothing more than a simple autonumbering column that you would add to each table and make it the clustered index instead of the GUID. The GUID could still be the PK. You wouldn't have to change any of the logic that uses the GUID.

You would STILL have to make sure you did regular index maintenance on your GUID column but that's true for any index.

In some cases and depending on the content of the table, you might not have to add an IDENTITY column. You could make the clustered index on a combination of a date column (to make the clustered index "ever increasing") and the GUID (to make the clustered index "unique").

--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.

Change is inevitable... Change for the better is not.

Helpful Links:
How to post code problems
How to Post Performance Problems
Create a Tally Function (fnTally)