UPDLOCK on a mult-table join

[drdeadpan]

Hi all,

Is this legal ?

SELECT a.col1,b.col2,c.col3
FROM tab1 a WITH (UPDLOCK) , tab2 b, tab3 c
WHERE a.col1 = b.col1
and b.col2 = c.col1

WIll the above cause a UPDLOCK on tab1 and not tab2 and tab3?

COmments,thoughts,criticisms?

I have a problem with a query that performs a multi-table join
to get column values and then one of the tables in the join is
being updated. I am getting DEADLOCKs and was wondering if I could
try and reduce that.

Also how can I find out what locks are in effect for a certain
query..Is it syslocks or are there any other tables..?

DrD

[Erland Sommarskog]

drdeadpan (vk***********@yahoo.com) writes:

Is this legal ?

SELECT a.col1,b.col2,c.col3
FROM tab1 a WITH (UPDLOCK) , tab2 b, tab3 c
WHERE a.col1 = b.col1
and b.col2 = c.col1

WIll the above cause a UPDLOCK on tab1 and not tab2 and tab3?
Yes. A table hint always affects one table only. You can use the
OPTION clause for hints that affects the entire SELECT statement.
However, you cannot specify locking hints in OPTION.
Also how can I find out what locks are in effect for a certain
query..Is it syslocks or are there any other tables..?

master.dbo.syslockinfo is the table to look in. Or use sp_lock.

Or for a more versatile of information, you use my aba_lockinfo,
available at http://www.sommarskog.se/sqlutil/aba_lockinfo.html.

--
Erland Sommarskog, SQL Server MVP, es****@sommarskog.se

Books Online for SQL Server SP3 at
http://www.microsoft.com/sql/techinf...2000/books.asp

[drdeadpan]

WIll look into it. Thanks

DrD