BLock Records Using UPDLOCK
Oct 2, 2006
Hi all,
here my question :
I have 2 applications.
connection 1.
one does select max(grp) from orv and one does select max(grp) from orh. orh is the historical file from orv. We did this to know which is the greather grp between these 2 files.
After having did this, we add 1 at grp field.
we insert into orv the record max(grp) + 1
connection 2.
an other application could insert at the same time record in this table orv with same parameters.
my problem is the following. I need to block record in orv table either on the select ( connection 1) or Insert ( connection 2) to avoid having select max(grp) + 1 on orv at connection 1 and Insert a record into orv at connection 2.
I believe I need to use HOLDLOCK, UPDLOCK.
but I have not the habitude to use them.
Can I do this ?
connection 1
select max(grp) from orv WITH HOLDLOCK
connection 2
what should I use to avoid lock when I need to insert into orv. ?
thanks for your quick answer
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Mar 12, 2007
Here is the situation i am stuck with, see the example first and below explained the problem:
-- 'SESSION A
create table foo (
id integer,
pid integer,
data varchar(10)
);
begin transaction
insert into foo values ( 1, 1, 'foo' )
insert into foo values ( 2, 1, 'bar' )
insert into foo values ( 3, 1, 'bozo' )
insert into foo values ( 4, 2, 'snafu' )
insert into foo values ( 5, 2, 'rimrom' )
insert into foo values ( 6, 2, 'blark' )
insert into foo values ( 7, 3, 'smeg' )
commit transaction
create index foo_id_idx on foo ( id )
create index foo_pid_idx on foo ( pid )
begin transaction
insert into foo values ( 9, 3, 'blamo' )
-- 'SESSION B
begin transaction
select id, data from foo with ( updlock, rowlock ) where id = 5;
-- Problem:
-- Uncommitted transaction in session A, with insert into table FOO, aquires lock on index foo_pid_idx which BLOCKS select with ( updlock, rowlock ) in session B.
-- Insert should aquire only exclusive rowlock. Why does insert block select with ( updlock, rowlock )?
Appreciate your help,
Rajesh.
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Dec 3, 2014
I have the following stored procedure to test scope of variables
alter proc updatePrereq
@pcntr int,
@pmax int
as
begin
[Code] ....
In the above script @i is declare in the if block only when the @pcntr value is 1. Assume the above stored procedure is called 5 times from this script
declare @z int
set @z = 1
declare @max int
set @max = 5
while @z <= @max
begin
exec dbo.updatePrereq @z, @max
set @z = @z + 1
end
go
As i said earlier `@i` variable exists only when `@pcntr` is `1`. Therefore when i call the stored procedure for the second time and so forth the control cannot enter the if block therefore @i variable wouldn't even exist. But the script prints the value in `@i` in each iteration, How comes this is possible should it throw an error saying `@i` variable does not exist when `@pcntr` values is greater than `1`?
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Apr 21, 2008
Any locking experts?
Are these two queries functionally identical (identical locking)?
--QUERY 1
update MyTable with (UPDLOCK)
set MyField = 1 where MyField2 = 2
--QUERY 2
update MyTable
set MyField = 1 where MyField2 = 2
In other words, is UPDLOCK redundant in an UPDATE query?
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Jul 26, 2006
Is there anything I can do from the Enterprise Manager console or fromwithin a JDBC connection to achieve the same effect as WITH(UPDLOCK)?Yes, I could change all of my SQL statements to include the lock... butisn't there any way to set or tweak something in SQL Server so that I won'thave to hack a lot of code* to make things concurrent? Perhaps a way to setUPDLOCK as the default behaviour for the server, or schema, or table, orsomething?Jerry H.* == The existing SQL has to remain as generic as possible so that it can beimplemented for four other databases.
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Jul 23, 2005
Hi all,Is this legal ?SELECT a.col1,b.col2,c.col3FROM tab1 a WITH (UPDLOCK) , tab2 b, tab3 cWHERE a.col1 = b.col1and b.col2 = c.col1WIll 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 jointo get column values and then one of the tables in the join isbeing updated. I am getting DEADLOCKs and was wondering if I couldtry and reduce that.Also how can I find out what locks are in effect for a certainquery..Is it syslocks or are there any other tables..?DrD
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Dec 3, 2007
I've got a SELECT WITH (UPDLOCK, ROWLOCK) WHERE followed by an UPDATE WHERE statement. The results of the SELECT statement are deserialized in C# and updates are made to the deserialized object. Then the object is serialized back into the table with the UPDATE statement. I've got this code running within a transaction scope with the ReadCommited isolation level.
My service receives requests to update data and the requests can come in on different threads. What I'm seeing, is that once in a while, the log messages from my application indicate that two different threads are able to issue the above SELECT statement and both are receiving results. This is a problem since the thread that issues the last UPDATE will overwrite the changes made by the first. Each thread has its own connection and transaction scope.
I've researched all over the place and have tried a few different things, but all things point to the fact that query hints are just hints and that SQL may or may not pay attention to them. If that's the case, how am I suppose to perform a SELECT with the intention of updating so that no one else can do the same? I haven't tried table level locking, but I'd really like to avoid that if possible.
-Mike
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Nov 21, 2015
The benifit of UPDLOCK is that it avoids deadlock in case both sessions run the below query at the same time.The table has clustered index on ID column
----session 1 --------
begin transaction
select * from a1
update a1
set id = 22
where id = 2
----session 2 --------
begin transaction
select * from a1
update a1
set id = 22
where id = 2
Now to avoid deadlock in the above scenario we should use (UPDLOCK) hint in the select statement.Now my question is that deadlock will be avoided in this case when both the sessions use UPDLOCK hint. If only one session uses UPDLOCk and other does not then there will be deadlock .For example session 1 uses UPDLOCK hint this will hold the U lock on the row, but the session 2 does not use this hint and apply shared lock on the same row. Now there will be deadlock when session 1 tries to update the record and is blocked by shared locks of session 2. same will be the case with session 2 and both will wait for each other and hence dead lock.so what steps can be taken to avoid deadlocks in this case. I do not want to use Snapshot isolation.
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Jul 15, 2015
just see same kind of two sql statement
BEGIN TRAN
SELECT *
FROM authors AU
WITH (HOLDLOCK, ROWLOCK)
WHERE AU.au_id = '274-80-9391'
COMMIT TRAN
BEGIN TRANSELECT *
FROM authors AU
WITH (UPDLOCK, ROWLOCK)
WHERE AU.au_id = '274-80-9391'COMMIT TRAN
i like to know what is the difference between HOLDLOCK and UPDLOCK in sql server. explain with example to better understand.
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Apr 25, 2008
This article instructed me on how to process rows from a table used as a data queue for multiple processes.
http://www.mssqltips.com/tip.asp?tip=1257
I tested this against the AdventureWorks DB (SQL 2005) and multiple SQL connections inside of Sql Mgmt. Studio).
Connection1:
BEGIN TRANSACTION
SELECT TOP 1 * FROM Production.WorkOrder WITH (updlock, readpast) --skips over locked rows
--COMMIT TRANSACTION
Connection2:
BEGIN TRANSACTION
SELECT TOP 1 * FROM Production.WorkOrder WITH (updlock, readpast) --skips over locked rows
COMMIT TRANSACTION
This works like I want where connection 2 skips over the locked row from connection 1 and gets the next available record from the table / queue. However, when I add ORDER BY tsql to each sql statement, connection 2 is now blocked waiting for Connection 1 to commit. (This is not what I want)
Connection1:
BEGIN TRANSACTION
SELECT TOP 1 * FROM Production.WorkOrder WITH (updlock, readpast) order by DueDate
--COMMIT TRANSACTION
Connection2:
BEGIN TRANSACTION
SELECT TOP 1 * FROM Production.WorkOrder WITH (updlock, readpast) order by DueDate --is blocked until connection 1 commits transaction
COMMIT TRANSACTION
How do I prevent blocking when using these locking hints with ORDER BY?
thanks
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Nov 12, 2015
Does a UPDLOCK request incur a physical write in any isolation level? (including read committed snapshot)
For example:
BEGIN TRANSACTION
SELECT col FROM dbo.test WITH ( UPDLOCK )
ROLLBACK
Is there any physical write taking place here?
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Mar 20, 2014
writing the query for the following, I need to collapse the continuity. If the termdate for an ID is one day less than the effdate of the next id (for the same ID) i need to collapse the records. See below example .....how should i write the query which will give me the desired output. i.e., get min(effdate) and max(termdate) if termdate is one day less than the effdate of next record.
ID effdate termdate
556868 1999-01-01 1999-06-30
556868 1999-07-01 1999-10-31
556869 2002-10-01 2004-01-31
556872 1999-02-01 2000-08-31
556872 2000-11-01 2004-01-31
556872 2004-02-01 2004-02-29
output should be ......
ID effdate termdate
556868 1999-01-01 1999-10-31
556869 2002-10-01 2004-01-31
556872 1999-02-01 2000-08-31
556872 2000-11-01 2004-02-29
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Apr 8, 2008
I've written a couple blocks but I have no idea when it comes to this one.
Create a PL/SQL block to retrieve the last name and department ID if each employee from the EMPLOYEES table
for those employees whose EMPLOYEE_ID is less than 114. From the values retreived from the employees table, populate two PL/SQL tables,
one to store the records of the employee last names and the other to store the records of their department IDs.
Using a loop, retreive the employee name information and salary infromation from the PL/SQL tables and doisplay it in the window,
using DBMS_OUTPUT.PUT_LINE. Display these details for the first 15 employees in the PL/SQL tables.
Any help helps
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May 18, 2006
If I've got a 64-bit OS such as Windows XP Professional x64 Edition running and I have the SQL Server 2005 Express Edition, is AES permittable or does TRIPLEDES still need to be used?
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Apr 10, 2008
Hello,
I have been experiencing a lot of blocking activity in my database. My trace results show that the following extended stored procedures sp_prepexec and sp_cursorfetch are executed by both the user causing the block and the user tha is blocked. Any ideas as to how to rectify this situation will be appreciated.
Regards,
Albert
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Dec 11, 2006
HI,
i'm trying to execute some sql using the Try.. Catch blocks.
Following code does not execute in Catch Block
Begin
begin try
insert into dbo.Test values (1,'aaa')
-- here we are inserting int value in identity field...
END TRY
Begin catch
PRINT 'TEST'
SELECT
ERROR_NUMBER() AS ErrorNumber,
ERROR_SEVERITY() AS ErrorSeverity,
ERROR_STATE() as ErrorState,
ERROR_PROCEDURE() as ErrorProcedure,
ERROR_LINE() as ErrorLine,
ERROR_MESSAGE() as ErrorMessage;
END Catch
End
GO
Whereas the following block works fine and the Catch block executes.
Begin
begin try
Select 1/0
--This causes an error.
END TRY
Begin catch
PRINT 'TEST'
SELECT
ERROR_NUMBER() AS ErrorNumber,
ERROR_SEVERITY() AS ErrorSeverity,
ERROR_STATE() as ErrorState,
ERROR_PROCEDURE() as ErrorProcedure,
ERROR_LINE() as ErrorLine,
ERROR_MESSAGE() as ErrorMessage;
END Catch
End
GO
Any idea why is it so?
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Mar 5, 2008
Can anyone guide me to write check block in SQL Server?
I Mean if blocking occurs, just inform people.
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Mar 18, 2008
Hi there! I need such thing: I have a data in Table A. When I get this data, I also increment this data by one, what I want is block Table A in order to other people will not get access to data.. I think about transactions, but are transactions reaaly blocks a table's content?
P.S. For example in MySQL there are Lock table command for blocking table for reading/writing. I need such thing/
Thanks
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Jul 3, 2007
Hi to everybody,
i have this problem.
sometimes a process in my SQL Server 2005 (upd 2) is blocked from itself. If I find in monitor it wait for a lock_M_Sch_M on a temporary table as you can see from
select * from sys.dm_tran_locks where request_session_id=51 and request_status <> 'GRANT'
resorce type : OBJECT
resource id : 218899226
request mode : Sch-M
request status WAIT
request_session id : 51
request life time : 33554432
or from
SELECT * FROM sys.dm_os_waiting_tasks WHERE SESSION_ID=51
waiting task address : 0x0000000000C2F198
session id : 51
wait type : LCK_M_SCH_M
resource address : 0x0000000201C71300
blocking task address : 0x0000000000C2F198
blocking session id = 51
resource description objectlock lockPartition=0 objid=218899226 subresource=FULL dbid=2 id=lock80d04900 mode=Sch-S associatedObjectId=218899226
I resolve this problem only with restart of sql server . that clear tempdb and eliminate this process
I think is not a problem about latch present from sql server 2000 sp4 (I read some document abount this problem)
So I haven't idea how to resolve this problem and how to kill this kind of process without to restart sql server
thanks in advance
Luca
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Oct 25, 2007
hi there,
to retrieve more then one record with a cursor we can use block cursor, so we have to set the cursor attribute SQL_ATTR_ROWSET_SIZE to some number...i am not getting any code example on this.
do anyone know this???
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Apr 12, 2006
Hi:
one of our study group members noticed a strange behavior and has the following question. Any thoughts are appreciated.
I am unable to understand as to why the CATCH block is not executed when an INSERT is made
On table T3 which is dropped after the first transaction.
The severity of Insert into t3 values (3) is Msg 208, Level 16, State 1, Line 2
Invalid object name 't3'.
BOL says TRY€¦CATCH constructs do not trap the following conditions:
Warnings or informational messages with a severity of 10 or lower.
Errors with severity of 20 or higher that terminate the SQL Server Database Engine task processing for the session. If an error occurs with severity of 20 or higher and the database connection is not disrupted, TRY€¦CATCH will handle the error.
Here is the script.
use tempdb
go
create table t1 (a int)
create table t2 (b int)
create table t3 (c int)
Begin tran
Insert into t1 values (1)
Insert into t2 values (2)
Insert into t3 values (3)
IF @@error <> 0
Rollback tran
else
commit tran
-------------------------------------------------------------
Select * from t1
Select * from t2
Select * from t3
-------------------------------------------------------------
Drop table t3
-------------------------------------------------------------
Set xact_abort on
Begin try
Begin tran insertNow
Insert into t1 values (1)
Insert into t2 values (2)
save tran insertNow
Insert into t3 values (3)
commit tran insertNow
End try
Begin Catch
IF (XACT_STATE()) = -1
BEGIN
PRINT 'The transaction is in an uncommittable state.' +
' Rolling back transaction.'
ROLLBACK TRANSACTION insertNow
END;
-- Test if the transaction is active and valid.
IF (XACT_STATE()) = 1
BEGIN
PRINT 'The transaction is committable.' +
' Committing transaction.'
COMMIT TRANSACTION insertNow
END
End Catch
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Feb 11, 2008
Ho do I clear a kill process blocking others to run
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May 18, 2004
Hello, everyone:
There are a lot of Access and Excel tables linked to my SQL Server (SQL2K SP3 on W2K). The end users update those likned tables. I am wondering if there is the block problem. If yes, how to prevent that? Thanks.
ZYT
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Sep 27, 2005
hi,
i've performed a test on 2 machines based on the topic above, but it doesn't seem like blocking each other... This is the context...
I've created a table call TEST_DEL i.e.
quote:CREATE TABLE test_del
(v_id INT,
desc CHAR(3)
)
In machine 1, i'm login as USER 1 and try to insert a set of records into the table
quote:
Machine 1
~~~~
BEGIN
DECLARE @li_num int,
@li_start int
SET @li_num = 100000
SET @li_start = 1
WHILE @li_start < @li_num
BEGIN
INSERT INTO test_del VALUES (@li_start, 'zzz', 'xxx')
IF (@li_start > @li_num)
BREAK
ELSE
SET @li_start = @li_start + 1
CONTINUE
END
END
In machine 2, i login in as USER 2 to retrieve the records at the same time...
quote:
SELECT * FROM test_del
but, the system still allow me to retrieve the records at the same time... May i know when will "Writer block reader, reader block writer" occur and in what situation
Thanks in advance
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Oct 10, 2006
Can anyone give a template for a stored procedure which involves a transaction and has a TRY CATCH block too...
Thanks in advance.
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Jun 14, 2006
I am writing some code generation stuff and I am trying to get a scriptlike this to work:IF (something)BEGINCREATE PROCEDURE WhateverASSELECT 1 as oneENDBut it complains about this, so I am guessing that I can't put thecreate prodcedure in an IF block.Does anyone know of a work around for this?
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Mar 5, 2008
Hi experts,
I have a job that has several steps.
One of the steps is of type T-SQL. I have an IF...ELSE block in it. If the if statement is true...perform an action.
Else exit from the job reporting failure.
I would like to know what sql stmts should i use to exit from the job (in the ELSE block)
I tried to use EXIT in the else stmt but it is not exiting from the job step.
Thanks in advance
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May 4, 2006
I'm working on a stored procedure which includes an IF statement at the end of the procedure which appends my sql call with two lines. But I'm getting an error that probably comes from the fact that I have a nested BEGIN END block in my overall procedure. Can anyone tell me if my assumption is correct and help polish of the syntax?
The error I'm getting is:
Msg 156, Level 15, State 1, Procedure payments_sp, Line 55
Incorrect syntax near the keyword 'AND'.
and the sql code looks like this:
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
ALTER PROCEDURE [dbo].[payments_sp]
-- Add the parameters for the stored procedure here
@payment_type varchar(15),
@mydate smalldatetime
AS
BEGIN
-- SET NOCOUNT ON added to prevent extra result sets from
-- interfering with SELECT statements.
SET NOCOUNT ON;
-- Insert statements for procedure here
DECLARE @myBool1 tinyint, @myBool12 tinyint
SET @myBool1 = 1
IF (@payment_type = 'CODE1' OR @payment_type = 'CODE4')
SET @myBool1 = 1
ELSE
-- the payment type must be 'CODE1' or 'CODE2'
-- set the value to false
SET @myBool1 = 0
IF (@payment_type = 'CODE3' OR @payment_type = 'CODE4')
SET @myBool12 = 1
ELSE
SET @myBool12 = 0
SELECT
SUM(Mydatabase.dbo.[PAYMENTS].[AMT_RECD])
FROM Mydatabase.dbo.[PAYMENTS]
INNER JOIN Mydatabase.dbo.[ACCT]
ON Mydatabase.dbo.[PAYMENTS].[SOME_UID] = Mydatabase.dbo.[ACCT].[SOME_UID]
WHERE Mydatabase.dbo.[ACCT].[CLIENT] = 'MY CLIENT'
AND Mydatabase.dbo.[PAYMENTS].[DATE_RECD] = @mydate
AND Mydatabase.dbo.[PAYMENTS].[BOOL] = @myBool1
AND Mydatabase.dbo.[PAYMENTS].[SOURCE] != 'val1'
AND Mydatabase.dbo.[PAYMENTS].[SOURCE] != 'val2'
AND Mydatabase.dbo.[PAYMENTS].[SOURCE] != 'val3'
IF (@payment_type = 'CODE3' OR @payment_type = 'CODE4')
BEGIN
AND Mydatabase.dbo.[PAYMENTS].[SOURCE] != 'val4'
AND Mydatabase.dbo.[PAYMENTS].[SOURCE] != 'val5'
END
END
GO
SET ANSI_NULLS OFF
GO
SET QUOTED_IDENTIFIER OFF
GO
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May 21, 2006
SELECT src_terrier.Areacode, src_terrier.siteref, src_terrier.estatename, src_terrier.Securitised, src_terrier.unitref, src_terrier.unittype, src_terrier.unittype_count, src_terrier.tenantname, src_terrier.tenantstatus, src_terrier.tenantstatus_count, src_terrier.unitstatus, src_terrier.unitstatus_count, src_terrier.floortotal, src_terrier.floortotocc, src_terrier.initialvacarea, src_terrier.initialvacnet, src_terrier.TotalRent, src_terrier.NetRent, src_terrier.FinalRtLsincSC, src_terrier.ErvTot, src_terrier.tenancyterm, src_terrier.landact, src_terrier.datadate, src_div_mgr.div_mgr, src_portfolio_mgr.portfolio_mgr, src_centre_list.propcat
FROM src_terrier INNER JOIN src_centre_list ON src_terrier.siteref = src_centre_list.Site_Ref AND src_terrier.Areacode = src_centre_list.Division INNER JOIN src_div_mgr ON src_centre_list.Division = src_div_mgr.division INNER JOIN src_portfolio_mgr ON src_centre_list.Portfolio_no = src_portfolio_mgr.portfolio_no
WHERE (src_terrier.datadate = @dt_src_date) AND (@chr_div is null or src_terrier.Areacode = @chr_div) AND (@vch_portfolio_no is null or src_centre_list.Portfolio_no = @vch_portfolio_no) AND (@vch_prop_cat is null or src_centre_list.propcat = @vch_prop_cat)
How can I modify this function in two ways
1. I want the value of src_terrier.siteref to be matched to a different table src_tbl_budget.siteref. I want all rows in src_terrier.siteref and only the one row from the new table where the siteref is matched.
2. Also part of the new query, not only do I want it to match the siteref, I also want it to only match the mm/yyyy of the parameter entered (src_terrier.datadate = @dt_src_date) in the WHERE statement.
Is that any simpler?
Regards
Toni Chaffin
aka Toni
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Dec 17, 2007
Help! On my desktop some security warning came up and my friend clicked "ok" when it said "block". Apparently it was warning her that internet explorer was trying to contact the internet. So...now internet explorer cannot display anything and it is the only browser I have on my computer. I am so frustrated I can't figure out what on earth I can change to fix this. Please...someone help me figure out why I can't contact the internet? My internet connection is fine, and the troubleshooting feature in explorer keeps telling me so.
Thanks!
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Sep 30, 2007
I guess this is a common problem because I ran into a lot of threads concerning the matter. Unfortunately, none of them helped my situation.I am throw a RAISERROR() in my sql and my vb.net try catch block is not detecting an error. SELECT '3'
RAISERROR('testerror',10,5) Dim con As New SqlConnection Dim _sqlcommand As New SqlCommand con = New SqlConnection(Spiritopedia.Web.Globals.Settings.General.ConnectionString) _sqlcommand.CommandType = Data.CommandType.StoredProcedure _sqlcommand.CommandText = "TestFunction"
_sqlcommand.Connection = con
'The value to be returned
Dim value As New Object
'Execute the command making sure the connection gets closed in the end
Try
'Open the connection of the command
_sqlcommand.Connection.Open()
'Execute the command and get the number of affected rows 'value = _sqlcommand.ExecuteScalar().ToString()
value = _sqlcommand.ExecuteScalar()
Catch ex As SqlException Throw ex Finally
'Close the connection
_sqlcommand.Connection.Close()
End Try
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Sep 3, 2004
Is there any way to clear out the exception from a previous Try/Catch block if I am nesting another Try/Catch block within it. I am executing a SQL Command and based on the Error number coming back decide whether or not to execute various other Sql commands. Now the Outer exception seems to be taking precedence over the Inner try block, and even though the code is stepped through for the inner try block it is never executed due to the Parent Exception. Is there any way to clear the exception received from the outer Try block? Here is a snippet of code:
Try
Cmd = New SqlCommand(Sql, Con)
Cmd.ExecuteNonQuery()
Catch t as SqlException
if t.Number = "2601" then
sql_upd = "<Text>"
Try
Cmd_upd = New SqlCommand(Sql_upd, Con)
Cmd_upd.ExecuteNonQuery()
Catch b as Exception
response.write("<Text>")
End Try
End If
End Try
Thanks,
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Jan 26, 2005
Forgive me if this is a stupid question.
How do you use a Server Side block cursor?
Lets say I have a db of 250,000 items and I want to retrieve the data 100 rows at a time.
How would I do this (using a block cursor, not in general)
thanks,
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