Record Locking In ADO.net/Sql Server
Feb 18, 2005
Currently I am working on asp.net Intranet system.I need some suggestion on records locking for Sqlserver & ASP.net.
I want to prevent two user to open the same record for modify.Means if some one has open one record (id=xxxxx) for modify then others should not be able to open same same record (id=xxxxx) for modify .otherwise if both user will open/update same record then information in database will not be updated correctly.
Any idea how we can do the record locking so that not two users can open same record(id=xxxxx) for modify.
Thanks in Advance
Arvind
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Apr 7, 2008
Hi,
We're running a Sage CRM install with a SQL Server 2000 database at the back end. We're using the Sage web services API for updating data and a JDBC connection to retrieve data as it's so much quicker.
If I retrieve a record using the JDBC connection and then try and update the same record through the web services, the query times out as if the record is locked for updates. Has anyone experienced anything similar or know what I'm doing wrong? If I just use DriverManager.getConnection() to establish the connection instead of the datasource, and then continue with the same code I don't get these record locking problems. Please find more details below.
Thanks,
Sarah
The JDBC provider for the datasource is a WebSphere embedded ConnectJDBC for SQL Server DataSource, using an implementation type of 'connection pool datasource'. We are using a container managed J2C authentication alias for logging on.
This is running on a Websphere Application Server v6.1.
Code snippet - getting the record thru JDBC:
DataSource wsDataSource = serviceLocator.getDataSource("jdbc/dsSQLServer");
Connection wsCon = wsDataSource.getConnection();
// wsCon.setAutoCommit(false); //have tried with and without this flag - same results
Statements stmt = wsCon.createStatement();
String sql = "SELECT * FROM Person where personID = 12345";
ResultSet rs = stmt.executeQuery(sql);
if(rs.next()){
System.out.println(rs.getString("lastName"));
}
if (rs != null){
rs.close();
}
if (stmt != null) {
stmt.close();
}
if (wsCon != null) {
wsCon.close();
}
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Oct 5, 2000
Hello,
I need help in record locking. As soon as user retrieve records I want to lock those records in database. When other user try to retrieve records from the same table i want to retrieve records those are not locked by other user. How do I do this? Please help...
Thanks in a millian.
Sarika
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Jul 26, 2001
Hello,
I have a database programmer who in his latest application has deployed manual record locking into code to release certain records to certain users of the application at specified times.
Does anyone know how manual record locking will affect the SQL 2K system? If at all? Are there some standard practices with manual record locking that should be enforced?
Thanks,
Brent.
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Sep 7, 2007
Project spec:
If user is making Delivery Order for sales order,
the other user cannot make Delivery order for same sales order
How to lock a sales-order record, so other user cant use it, except for reporting (read only). I dont want to use a field since it has a lot of weakness. I am using VB6 and connect with ADO
Thanks
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Jan 3, 2000
I am writing a VB program, which needs to update record A in one table using transaction control (BeginTrans & CommitTrans). But due to the page-level locking, before the "CommitTrans", other users couldn't not read other records in the same table.
Is there any way that I can do the record/row level locking? If possible, could you provide me some VB source code? Such as how to use "DBCC ROWLOCK" or how to set for row-level locking.
Thanks for your kind help.
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Nov 15, 2004
Hi all,
I'm working on a Planning Databse for a factory that allows jobs to be allocated to machines and to be given a priority. This info. is displayed on an Access 2000 form e.g.
MACHINE ONE MACHINE TWO
Priority Job Number Priority Job Number
1 J111 1 J654
2 J562 2 J865
3 j231 3 J821
Both the Production Manager and the Factory Manager have this form open at all times. The problem is this, if for example the Factory Manager changes the priority of a job on his PC, the change is not shown on the Production Managers PC (cos' his screen has not been refreshed with update) The Production Manager therefore has old data on his screen and could mistakenly think that the job priority had not changed at all...
I have managed to write some VBA code to get round this but I was wondering if there was any way of 'pushing ' changes to the front-end when they are made or of using record-locking etc. to achieve the same affect...
Thanks
M
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Dec 9, 2005
I am running an Access 2000 front end and MS SQL2000 as a backend and I am having problems with record locking.
I have just found out that If you use ODBC then Access acts as if No Locks are set. In an ideal world I need the record to be locked by a user as soon as they move onto it. If not as soon as they start editing it?
Cheers.
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May 3, 2006
Hi there,
Up until this point I've been quite lazy in trying to understand how record locking really works in SQL server however one of my applications now has a bug so the time has come for me to take the issue seriously.
Basically, a user clicks a button in my app and updates a field in a table in SQL Server (say at 10:34:55). At the almost exactly the same time (lets say 10:34:57) another user tries to update the same record (not necessarily the same field) but the second users update is not connected to the database.
How can I store the second users update and then commit to database once the first user is finished...is it possible or do i need to approach this from a different angle?
Thanks
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Jul 23, 2005
I'm trying to figure out what happened.I have have two Tables in SQLServer called "Contacts", and "Jobs"Whenever someone changes a record in either table I update two fieldscalled "Modby" and "Moddt" with a trigger. The Trigger may alsocontain other things as well.Here's the wierd thing.If the Modby Moddt statement is the first statement in the trigger Idon't get a "record changed by another user" but if it comes later inthe trigger I do.I think it has something to do with the LockDelay Key but I'm not sure.Any Ideas?
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Jul 23, 2005
Is there a way using ADO.NET to lock a record so that you can performan atomic Test and Set operation on one of its fields?I want to set an application level lock bit on a record's field (set itfrom 0 to 1) and at the same time determine that it was 0 before Ibegan and that I was the one who set it to 1, or that it was 1 before Igot to it (and thus I do not own the lock to the record).I don't see anything that explains if this can be done using ADO.NETusing MSSQL. Any help is greatly appreciated.
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Mar 15, 2007
I found this interesting paper at http://ftp.sas.com/techsup/download/v8papers/odbcdb.pdf, comparing OLEDB to ODBC.
It says that OLEDB provides record locking where ODBC doesn't. I can't quite reconcile that statement; what does it mean? How is the access layer involved in determining type of locks used by the server in executing a statement?
.B ekiM
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Aug 16, 2007
From SQL Server Books Online, there is a topic: Concurrency Effects, and did mention the following side effects:
- Lost updates.
- Uncommitted dependency (dirty read).
- Inconsistent analysis (nonrepeatable read).
- Phantom reads.
Can someone please tell me which type of Isolation Levels in the Database Engine to avoid the above side effects respectively.
For Record Locking issue:
Example, two editors make an electronic copy of the same document. Each editor changes the copy independently and then saves the changed copy thereby overwriting the original document. The editor who saves the changed copy last overwrites the changes made by the other editor.
This problem could be avoided if one editor could not access the file until the other editor had finished and committed the transaction.
For the above example, is it possible to do like this way:
Editor 1: SELECT and Lock a record
Editor 2: Before SELECT the record, check for the record whether it is locked or not. If it is not lock, then the record can be selected
Please advise.
Thanks.
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Feb 25, 2004
I have built my own functions in the past that involve a timestamp and record lock column in each table (to support some other DB).
I am currently using SQL 2000 and was wondering if there is a better (OK, easier) way to lock records and even prevent edits from taking place when a record is open.
Any input appreciated.
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Jul 15, 2007
I've been considering implementing a P2P Transactional Replication concept using three different sites. My qustion is:
Instead of have records only available for editing by specific sql servers (partitioning), can I implement some sort of record locking? For exampel all sql nodes have r/w access to all data unless one sql node has the record locked?
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Jul 20, 2005
I have a problem with record locking / blocking within an application.The app is quite straight forward. Written in Delphi 5 using BDE toaccess a SQL 7 database (Win2K server).Every so often the users (when they bother to tell me) find that theapplication locks up and they are unable to work. No errors areproduced (error trapping in the app is good). They 'shout round' toeach other and get someone to exit the data entry screen. This seemsto free up the locking/blocking issue.There are about 50,000 records in the table (script below) and it isaccessed through a simple query (script below). All users will accessthis in the same way. I'm assuming that a new record is being editedwhen the problem occurs, but this shouldn't cause locking/blockinguntil it gets committed (right ?).The problem is tracking down the source of this and finding thepattern which I can work back from. I've used Erland's aba_lockinfoscript (a few months back admittedly so will re-visit this), butnothing obvious is jumping out at me.No other tables should be in use at this point.Any suggestions ?ThanksRyan/* Code for query component - users navigate to the record they needto editthere could be 15,000 records showing as outstanding - perhaps thisis the area that I need to re-visit so that less records can be edited? */SELECT *FROMPostReceivedWHEREToDelete = 0 ANDCompleted <> 1ORDER BYPostID/* Table in question */if exists (select * from sysobjects where id =object_id(N'[dbo].[PostReceived]') and OBJECTPROPERTY(id,N'IsUserTable') = 1)drop table [dbo].[PostReceived]GOCREATE TABLE [dbo].[PostReceived] ([PostID] [int] IDENTITY (1, 1) NOT NULL ,[Type] [varchar] (100) NULL ,[ClientsName] [varchar] (100) NULL ,[DateReceived] [datetime] NULL ,[EnteredBy] [varchar] (100) NULL ,[AssignedTo] [varchar] (100) NULL ,[DateAssignedTo] [datetime] NULL ,[Adviser] [varchar] (100) NULL ,[TargetDate] [datetime] NULL ,[CompletionDate] [datetime] NULL ,[Completed] [bit] NULL ,[KeyAccount] [varchar] (100) NULL ,[Notes] [text] NULL ,[Specific1] [varchar] (20) NULL ,[Specific2] [varchar] (20) NULL ,[Specific3] [varchar] (20) NULL ,[Specific4] [varchar] (20) NULL ,[Specific5] [varchar] (20) NULL ,[ToDelete] [bit] NULL ,[EnterUser] [varchar] (20) NULL) ON [PRIMARY] TEXTIMAGE_ON [PRIMARY]GO
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Aug 27, 2007
can someone pls show me a way to get an unique sequence at below senario:
PC1 & PC2 using their own local client progam to access to Database Server at SERVER1.
In the SERVER1, there is a table SEQUENCE in a database DATABASE1.
And the table's structure of SEQUENCE are SeqType & SeqNo.
Here is the sample data:
SeqType SeqNo
Invoice 100
DeliveryOrder 200
Now, how to prevent PC1 & PC2 to get a same Invoice No. if they request the Invoice No. at the same time?
Is it possible to lock the record Invoice when i perform a SELECT statement, then i update the Invoice to 101, lastly release the lock for Invoice?
pls advise. thanks.
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Feb 13, 2008
We have a linked server configured on our SQL Server 2005 server that points to our iSeries. A step in a scheduled job successfully updates data in tables on the iSeries using an update query and the 4-part naming convention (job reports success and updates can be verified), but it appears to leave locked records and open connections on the iSeries. No open sessions showing in SQL Activity Monitor.
The linked server is configured using Microsoft's OLEDB Provider for DB2. Are there additional settings that can be configured on the linked server to prevent this behavior or is this an issue that need needs to be addressed on the iSeries? A timeout setting perhaps (not sure if this fixes the record locks though)?
Any help is greatly appreciated.
KS
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Mar 1, 2006
Hi
Can anyone advise me as to how I can add the date and time to 2 columns in the sql server database for each record that is added. I'd prefer not to use the webform. Can sql server add the date automatically to the row?
thanks
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Jun 28, 2001
I have a table X with 61390 rows on it. IT is a crucial table which is being read and updated constantly. If I create a clustered index on the Primary Key (identity column) and run UPDATE x SET c1 = 1234 where PKCOL = 4321 the best lock I can get is a table Lock. If I create a compound non-clustered index on C1 and PKCOL the best lock I can get is a Page Lock. PAge Lock is OK but as this table is in High demand I want a row lock so others can carry on referenceing other parts of the table. WHy does it take a page lock and not a Row lock?
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Jul 7, 1999
Hi,
We are becoming increasingly more involved with SQL Server 7.0 development.
Can someone show me a good example of ROW LOCKING with exclusive and share
modes?
If I am starting a transaction with a SELECT and later an UPDATE, what is
the best way to handle locking?
Thank you for any help on this issue.
Steve
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Mar 6, 2007
is there a way of locking db on server. i am doing a overtime and pay system but there is a few members of IT staff that are very nosey and this is senstive information and i dont want them looking at the tables on the server can these be locked for only me to view
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Mar 22, 2007
Hello,
I'm trying to determine if a row in a table is locked. First, I issue a lock on some rows. Then, I query the syslockinfo table to see which rows are locked. It tells me which rows are locked, but it returns a hashed resource value that, I guess, is somehow related to the key. How can I un-hash the value? Or, how can I hash my own key so that I can compare it with the hashed value? I have tried using the HashBytes function, but I don't know what is actually being hashed when the row is locked.
For example:
begin transaction
select * from test with (rowlock, updlock)
select * from master..syslockinfo
where rsc_objid = (select id from sysobjects where name = 'test') and req_mode = 4
returns:
rsc_text = (010086470766); rsc_bin = 0x000708001374FC020100010086470766
Thanks.
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Apr 23, 2007
Hi
I have a setting where two Web Servers access the same SQL Server database. To gaurantee consistent data writes and reads I need to lock part of the database in special conditions.
I know exactly when I need particular tables of the database to be locked, but I am in doubt of how to do it. Does SQL Server 2005 have any mechanism for providing locks gauranteed to free the lock if one of the web servers crash - or if SQL Server itself crashes?
/Bezbos
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Feb 28, 2006
Hi,
How can i handle record locking in sql server?
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Jan 5, 2004
In the application I'm working on, I need to be able to use different locks on my records during certain transactions. I need to know how to do this programmatically from within VB.net. If someone can show me an example of how to do this or show me where I could find some, I'd appreciate that.
Thanks.
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Jul 23, 2005
Hi All,According to my observation using SP_WHO2 in my database, some INSERTstatements are getting blocked by SELECT statements. Though theblockingSELECT statement is having ReadPast hint, i think, it will only readpastlocked resources but will not guarantee the select statement itself notblocking other statements(in my case Insert). According to my knowledgeandinformation, select statements take shared locks but why then thesestatements are blocking insert statements?Can there be any other solution other than using NoLock hint as thishintmake sure no shared locks are issued but it can read uncommited data.Need help urgently.ThanksRitesh
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Dec 8, 2006
How to avoid table locks during simultaneous addition, deletion and updates of 50,000 records or more. I am using SQL Server 2005 interfacing with Java.
Thanks,
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Mar 27, 2007
Hi...
i hv a database (sql server 2000) where i got locking on many tables and my application was down.
I restarted the sql server and the application was fine but after five minutes the same locking issue started happening. I did a index rebuild the next time on all indexes and everything was fine.But i cannot relate how locking occured and why it was not after index rebuild.Can anyone shed some light on this or anyone had similar experience... cos i cannot figure out a way on this.
Thanks in advance
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Jan 29, 2008
Hi pardon my ignorance but I wonder if someone could answer a few questions for me.
I am writing a program which will be used by perhaps upto 100 users at a time. The program sits on any number of PCs and loads user specific data to a given PC according to who has logged on to windows on that PC.
A number of data items loaded from the user table have to be unique as they are usernames for other systems that my program simplifies access to.
So when a user logs on to my program for the first time a row is created for them in the user table (indexed by a GUID and their unique network name). The other unique fields are left blank and the user is given an opportunity to fill these details in.
Before writing these details to the user's row in the 'users table' the program loads the whole user table down and checks that these items are unique before committing them to that user's row in the table.
The problem of course is that if between the program downloading the user table into a local datatable, checking the values are unique and then actually writing them someone else writes the same data into their row then 2 users end up with the same data - which shouldn't be allowed. i.e. 2 users can't have the same user name for the other software.
How can I solve this problem with locking? Once the user table is downloaded and in a locel datatable presumably the table is no longer locked so another user could write data to the table.
I acutally think this is going to be a pretty rare occourance but I still want to try to cover all eventualities.
I suspect the problem is the way my program is going about the checking.
Should I use an SQL insert statement like??
If exists(SELECT username from users where username=@username)
BEGIN
RAISEERROR("Username already exists")
END
ELSE
BEGIN
INSERT etc
If so I guess this will simplify my code. Is this the correct thing to do? And then just trap the errors that arise if a duplicate does arise?
Also some more general questions.
1)I presume 2 users simultaneously looking up data from 2 different rows in a table doesn't lock the table so one search fails? I use the code below having set up a command to run a stored procedure to search for a user by their network name.
Dim lclRowRet As SqlDataReader
lclRowRet = LoadUserCommand.ExecuteReader(CommandBehavior.SingleRow)
lclRowRet.Read()
2) I presume writing data to my user table a row at a time will also not cause a lock. I create a command object with all the row values in and then do a command.executenonquery()
As a rule I close all my connections as soon as I'm done with them.
Many thanks for your help in advance.
nik
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May 9, 2006
I'm running a website on IIS 6.0 w. ASP.Net 2.0 and SQL Server Express 2005 via the native client. The connection string is fairly standard:
<add name="SiteSqlServer" connectionString="Data Source=.SQLEXPRESS;AttachDbFilename=c:DotNetNukeApp_DataASPNETDB.MDF;Integrated Security=True;User Instance=True" providerName="System.Data.SqlClient"/>
I find that after the website has been running for a while I can no longer open the database using SQL Server Management Studio Express (I get an error indicating that the physical file has been locked). Even if I shutdown and restart both IIS and SQL Server, it remains locked and can only be opened once I find and "End Process" all the sqlservr.exe instances from the Task Manager.
Is this a known issue? Any way to find out what is locking the database, or any specific configuration to check?
thanks
Steve
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Apr 22, 2015
We have one table.We have updated the status for one column to 1 and we did not committed the transaction. Can we do an another update on another row.
In below example i am updating GEO_D and transaction is not committed. Now my requirement is we have to update other records (not Geo_D). If try to update GEo_D it should wait.
IF OBJECT_ID('TEMPDB..##TEMP_STSTUS') IS NOT NULL
DROP TABLE ##TEMP_STSTUS
CREATE TABLE ##TEMP_STSTUS
(
ID INT IDENTITY(1,1)
,NAME VARCHAR(10)
,STSTUS VARCHAR(10)
)
INSERT INTO ##TEMP_STSTUS SELECT 'GEO_D','0'
[Code] ....
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