SQL Related Articles: Logout on SQL tables
2002-11-30 -- Jim Kane
Newsgroups: comp.lang.clarion
Logout is essential for related table actions. I would not do that type of
thing without logout.
The degree of locking logout causes is controlled by the issolation level
for the transaction on your back end, and the code inside the
your logout.
MSSQL 6.5 and 7.0 perform locking in very different ways. Once you
understand the effects of isolation level on your back end, then you should
set the isolation level you need using prop:logoutisolationlevel or with
prop:sql. you can also set prop:isolationlevel but I like the default
value.
The equates I use in conjunction with prop:logoutIsolationLevel are:
readuncommitted equate(1)
readcommitted equate(2)
RepeatableRead equate(4)
Serializable equate(8)
Most any sql book has descriptions of these. The best book I've found with
the most extensive coverage of locking for mssql is Inside SQL Server 7.0 by
delaney. they have two chapters on locking and hints.
Jim Kane
"Cliff Campbell & Associates" wrote in message
news:V44B9.12372$cP3.23230@news.iol.ie...
> Hi,
>
> Can anyone tell me if LOGOUT locks tables using SQL server and ODBC or
> not...or sometimes? It appears if using the following type example code
that
> it does. Should it?
>
> bGoodFlag = False
> LOGOUT(Table1, table2,....,tablex)
> If DeleteFromTable1(...)
> If DeleteFromTable2(...)
> If DeleteFromTable3(...)
> .
> .
> bGoodFlag = True
> end
> end
> end
> If bGoodFlag
> commit
> else
> rollback
> end
>
> Am I right to be using LOGOUT etc. above or should I just remove it. I am
> covering for events like, for example, if the third delete function fails.
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