Very true. It all depends on what you want to do with the max + 1 after
you get it.
-----Original Message-----
From: Chris Hagemaier
[mailto:mssqldba-ezmlmshield-x48517834.[Email address protected]
Sent: Thursday, April 28, 2005 11:41 AM
To: LazyDBA Discussion
Subject: RE: Sequential Number Creation
Care must be taken however. Suppose the max + 1 is selected by user1
but not commited. Then suppose user2 selects the same max + 1 so
that user1 and user2 have the same number. If they both committed
then the app would attempt to insert identical numbers into the
target table (which may be good or bad depending on what you're
trying to do).
We wrote such an inhouse app sveral years ago (in Oracle but so what).
We didn't select the max+1 until a final commit and even then it was
possible for two clerks accepting payments at the counter to get the
same receipt number. So we constructed a table of sequence values (one
column only with a unique constraint (index)). When max+1 was selected
it was immediately inserted back into the sequence table and then all
work was commited. If two users attempted an insert of the same number
one of them would violate the unique constraint, the app would catch it
and deal with it. And....... it worked. Just something to consider.
-----Original Message-----
From: Laurie Solgon
[mailto:mssqldba-ezmlmshield-x70238726.[Email address protected]
Sent: Thursday, April 28, 2005 11:24 AM
To: LazyDBA Discussion
Subject: RE: Sequential Number Creation
Select max(numb_field) + 1
This can be used to insert later.
-----Original Message-----
From: Hornak Wayne
[mailto:mssqldba-ezmlmshield-x84458119.[Email address protected]
Sent: Thursday, April 28, 2005 11:13 AM
To: LazyDBA Discussion
Subject: Sequential Number Creation
How do I create a unique sequential number within the result of a sql
statement?
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