I want to run multiple instances of powershell to collect data from Exchange. In powershell, I use invoke-sqlcmd to run various SQL commands from powershell.
SELECT TOP 1 SmtpAddress FROM [MMC].[dbo].[EnabledAccounts]
where [location] = '$Location' and Script1 = 'Done' and (Script2 = '' or
Script2 is null)
When running more than one script, I see both scripts accessing the same record. I know there's a way to update the record, to lock it, but not sure how to write it out. TIA:-)
The database management system (I'll assume SQL Server) will handle contention for you. Meaning, if you have two sessions trying to update the same set of records, SQL Server will block one session while the other completes. You don't need to do anything to explicitly make that happen. That said, it's a good idea to run your update in a transaction if you are applying multiple updates as a single unit; a single change occurs in an implicit transaction. The following thread talks more about transactions using Invoke-SqlCmd.
Multiple Invoke-SqlCmd and Sql Server transaction
Related
I am frequently testing certain areas on a development server and so running a pre-defined SQL statement to truncate the tables in question before testing again. It would only be a slip of a key to switch to the live server.
I'm looking for an IF statement or similar to prevent that.
Either to check the server name, database name, or even that a certain record in a different table exists before running the query.
Any help appreciated
For such cases I use stored procedures. I'd call them TestTruncateTables, etc.
Then instead of calling TRUNCATE TABLE you should CALL TestTruncateTables.
Just make sure that the procedures are not created on the live server. If by any chance you happen to run CALL TestTruncateTables on the live server you only get an error about non-existing proc.
I have multiple select queries which I want to execute asynchronously.
How can I do this in oracle sql ?
I basically want to test something and so want to simulate workload so I don't really care about the result and I know I can do this in multiple threads but this is specific and so would prefer if I can do this entirely in sql. procedures are fine though.
NOTE: there are no update queries only select.
I read about nowait but am not sure how to use it in oracle.
I tried something like -
select * from foo with(nowait) where col1="something";
This is the error I got -
with(nowait)
*
ERROR at line 3:
ORA-00933: SQL command not properly ended
The Oracle info on NOWAIT says:
Specify NOWAIT if you want the database to return control to you immediately
if the specified table, partition, or table subpartition is already locked by
another user. In this case, the database returns a message indicating that the
table, partition, or subpartition is already locked by another user.
This will not do what you want.
Asynchronous queries are an application thing, not a SQL thing. For example I can open TOAD and open a dozen windows and run long queries in all of them and still open another window and run another query. I could open a dozen instances of SQLPLUS and do the same thing. Nothing in the query lets me do this, it's in the application.
I think you could use DBMS_SCHEDULER to schedule some sql or procs that execute SQL.
However this is probably not the best way to do this
There are tools for this. The best way maybe to write a procedure you can call from the web and then you can use any performance testing tool that can make a web call...its worked for me before.
You may also consider:
http://sqlmag.com/database-performance-tuning/testing-heavy-load-simulating-multiple-concurrent-operations
I am trying to use an ODBCdataadapter in C# to run a query which needs to select some data into a temporary table as a preliminary step. However, this initial select statement is causing the query to terminate so that data gets put into the temp table but I can't run the second query to get it out. I have determined that the problem is the presence of two select statements in a single dataadapter query. That is to say the following code only runs the first select:
select 1
select whatever from wherever
When I run my query directly through SQL Server Management Studio it works fine. Has anyone encountered this sort of issue before? I have tried the exact same query previously on similar databases using the same C# code (only the connection string is different) and had no problems.
Before you ask, the temp table is helpful because otherwise I would be running a whole lot of inner select statements which would bog down the database.
Assuming you're executing a Command that's command type is CommandText you need a ; to separate the statements.
select 1;
select whatever from wherever;
You might also want to consider using a Stored Procedure if possible. You should also use the SQL client objects instead of the ODBC client. That way you can take advantage of additional methods that aren't available otherwise. You're supposed to get better perf as well.
If you need to support multiple Databases you can just use the DataAdapter class and use a Factory o create the concrete types. This gives you the benefits of using the native drivers without being tied to a specific backend. ORMS that support multiple back ends typically do this. The Enterprise Library Data Access Application Block while not an ORM does this as well.
Unfortunately I do not have write access to the DB as my organization has been contracted just to extract information to a data warehouse. The program is one generalized for use on multiple systems which is why we went with ODBC. I suppose it would not be terrible to rewrite it using SQL Management Objects.
ODBC Connection requires a single select statement and its retrieval from SQL Server.
If any such functionality is required, a Hack can do the purpose
use the query
SET NOCOUNT ON
at the top of your select statement.
When SET NOCOUNT is ON, the count (indicating the number of rows affected by a Transact-SQL statement) is not returned.
When SET NOCOUNT is OFF, the count is returned. It is used with any SELECT, INSERT, UPDATE, DELETE statement.
The setting of SET NOCOUNT is set at execute or run time and not at parse time.
SET NOCOUNT ON mainly improves stored procedure (SP) performance.
Syntax:
SET NOCOUNT { ON | OFF }
When running a stored procedure (from a .NET application) that does an INSERT and an UPDATE, I sometimes (but not that often, really) and randomly get this error:
ERROR [40001] [DataDirect][ODBC Sybase Wire Protocol driver][SQL Server]Your server command (family id #0, process id #46) encountered a deadlock situation. Please re-run your command.
How can I fix this?
Thanks.
Your best bet for solving you deadlocking issue is to set "print deadlock information" to on using
sp_configure "print deadlock information", 1
Everytime there is a deadlock this will print information about what processes were involved and what sql they were running at the time of the dead lock.
If your tables are using allpages locking. It can reduce deadlocks to switch to datarows or datapages locking. If you do this make sure to gather new stats on the tables and recreate indexes, views, stored procedures and triggers that access the tables that are changed. If you don't you will either get errors or not see the full benefits of the change depending on which ones are not recreated.
I have a set of long term apps which occasionally over lap table access and sybase will throw this error. If you check the sybase server log it will give you the complete info on why it happened. Like: The sql that was involved the two processes trying to get a lock. Usually one trying to read and the other doing something like a delete. In my case the apps are running in separate JVMs, so can't sychronize just have to clean up periodically.
Assuming that your tables are properly indexed (and that you are actually using those indexes - always worth checking via the query plan) you could try breaking the component parts of the SP down and wrapping them in separate transactions so that each unit of work is completed before the next one starts.
begin transaction
update mytable1
set mycolumn = "test"
where ID=1
commit transaction
go
begin transaction
insert into mytable2 (mycolumn) select mycolumn from mytable1 where ID = 1
commit transaction
go
How is it possible to run a stored procedure at a particular time every day in SQL Server Express Edition?
Notes:
This is needed to truncate an audit table
An alternative would be to modify the insert query but this is probably less efficient
SQL Server Express Edition does not have the SQL Server Agent
Related Questions:
How can I schedule a daily backup with SQl Server Express?
Scheduled run of stored procedure on SQL Server
Since SQL Server express does not come with SQL Agent, you can use the Windows scheduler to run a SQLCMD with a stored proc or a SQL script.
http://msdn.microsoft.com/en-us/library/ms162773.aspx
I found the following mechanism worked for me.
USE Master
GO
IF EXISTS( SELECT *
FROM sys.objects
WHERE object_id = OBJECT_ID(N'[dbo].[MyBackgroundTask]')
AND type in (N'P', N'PC'))
DROP PROCEDURE [dbo].[MyBackgroundTask]
GO
CREATE PROCEDURE MyBackgroundTask
AS
BEGIN
-- SET NOCOUNT ON added to prevent extra result sets from
-- interfering with SELECT statements.
SET NOCOUNT ON;
-- The interval between cleanup attempts
declare #timeToRun nvarchar(50)
set #timeToRun = '03:33:33'
while 1 = 1
begin
waitfor time #timeToRun
begin
execute [MyDatabaseName].[dbo].[MyDatabaseStoredProcedure];
end
end
END
GO
-- Run the procedure when the master database starts.
sp_procoption #ProcName = 'MyBackgroundTask',
#OptionName = 'startup',
#OptionValue = 'on'
GO
Some notes:
It is worth writing an audit entry somewhere so that you can see that the query actually ran.
The server needs rebooting once to ensure that the script runs the first time.
Create a scheduled task that calls "C:\YourDirNameHere\TaskScript.vbs" on startup. VBScript should perform repeated task execution (in this example, it's a 15 minute loop)
Via command line (must run cmd.exe as administrator):
schtasks.exe /create /tn "TaskNameHere" /tr "\"C:\YourDirNameHere\TaskScript.vbs\" " /sc ONSTARTUP
Example TaskScript.vbs: This executes your custom SQL script silently using RunSQLScript.bat
Do While 1
WScript.Sleep(60000*15)
Set WshShell = CreateObject("WScript.Shell")
WshShell.RUN "cmd /c C:\YourDirNameHere\RunSQLScript.bat C:\YourDirNameHere\Some_TSQL_Script.sql", 0
Loop
RunSQLScript.bat: This uses sqlcmd to call the database instance and execute the SQL script
#echo off
sqlcmd -S .\SQLEXPRESS -i %1
If you are using Express Edition, you will need to use the Windows Scheduler or the application connecting to the server in some way.
You would use the scheduler to run sqlcmd. Here are some instructions for getting the sqlcmd working with express edition.
SQL Scheduler from http://www.lazycoding.com/products.aspx
Free and simple
Supports all versions of SQL Server 2000, 2005, and 2008
Supports unlimited SQL Server instances with an unlimited number of jobs.
Allows to easily schedule SQL Server maintenance tasks: backups, index rebuilds, integrity checks, etc.
Runs as Windows Service
Email notifications on job success and failure
Since another similar question was asked, and will likely be closed as a duplicate of this one, and there are many options not mentioned in the answers already present here...
Since you are using SQL Express you can't use SQL Server Agent. However there are many alternatives, all of which you can schedule using AT or Windows Task Scheduler depending on your operating system:
VBScript
C# command line app
batch file with SQLCMD
PowerShell
All of these languages/tools (and many others) have the capacity to connect to SQL Server and execute a stored procedure. You can also try these Agent replacements:
SQLScheduler
Express Agent
Standalone SQL Agent (beta)
The easiest way I have found to tackle this issue is to create a query that executes the stored procedure then save it. The query should look similar to this one below.
use [database name]
exec storedproc.sql
Then create a batch file with something similar to the code below in it.
sqlcmd -S servername\SQLExpress -i c:\expressmaint.sql
Then have the task scheduler execute the batch as often as you like
Another approach to scheduling in SQL Express is to use Service Broker Conversation Timers. To run a stored procedure periodically, which you can use to bootstrap a custom scheduler.
See eg Scheduling Jobs in SQL Server Express
You could use Task Scheduler to fire a simple console app that would execute the Sql statement.
As you have correctly noted, without the agent process, you will need something else external to the server, perhaps a service you write and install or Windows scheduler.
Note that with an Express installation for a local application, it is possible that the machine may not be on at the time you want to truncate the table (say you set it to truncate every night at midnight, but the user never has his machine on).
So your scheduled task is never run and your audit log gets out of control (this is a problem with SQL Server Agent as well, but one would assume that a real server would be running non-stop). A better strategy if this situation fits yours might be to have the application do it on demand when it detects that it has been more than X days since truncation or whatever your operation is.
Another thing to look at is if you are talking about a Web Application, there might be time when the application is loaded, and the operation could be done when that event fires.
As mentioned in the comment, there is sp_procoption - this could allow your SP to run each time the engine is started - the drawbacks with this method are that for long-running instances, there might be a long time between calls, and it still has issues if the engine is not running at the times you need the operation to be done.
Our company also use SQLEXPRESS and there is no SQL Agent.
Since there is no marked answer as "right" and all the solutions are quite complex I'll share what I did there. May be its really bad, but it worked great to me.
I've chosen operations of Insertion (people do) to a table that got closely the same time range i needed and made a trigger "ON INSERT" that applies needed function.