Gerard's codebase
Over the years I have generated lots of little sub programs and stored away acres of useful code snippets. The problem is always to locate them.
Even more time wasting is forgetting how to do simple things when you havnt developed in an environment for a few years (or even a few months)
My new years resolution is to start putting them up in a common place as I produce them. (thanks google)
They are handy for me and, with a bit of a clean up and documentation, they might be handy for others if they wander in here.
Gerard 2008
Tuesday, November 18, 2008
SQL- Strpping out time from DateTime - going back to weekdays
DECLARE @Date As DATETIME
DECLARE @CurDay AS INTEGER
SET @CurDay = DATEPART(weekday,GETDATE())
SET @Date =
CASE
WHEN 1 = @CurDay THEN GETDATE()
WHEN 2 = @CurDay THEN DATEADD(DAY,-1,GETDATE())
WHEN 3 = @CurDay THEN DATEADD(DAY,-2,GETDATE())
WHEN 4 = @CurDay THEN DATEADD(DAY,-3,GETDATE())
WHEN 5 = @CurDay THEN DATEADD(DAY,-4,GETDATE())
WHEN 6 = @CurDay THEN DATEADD(DAY,-5,GETDATE())
WHEN 7 = @CurDay THEN DATEADD(DAY,-6,GETDATE())
ELSE GETDATE()
END
--Strip out the time part
SET @Date = CAST((STR( YEAR( GETDATE() ) ) + '/' + STR( MONTH( GETDATE() ) ) + '/' + STR( DAY( GETDATE() ) ) )AS DATETIME )
Print @Date
Avoid cursors in SQL Server with these methods to loop over records
Matthew Schroeder
11.17.2008
Rating: --- (out of 5)
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Method 1: Temp table with identity column In the first approach, we will use a temp table with an identity column added to allow for row-by-row selection. If you're performing an INSERT/UPDATE/DELETE, be sure to use the explicit transactions. This vastly reduces the load on your log file by committing per loop, and it prevents huge rollbacks in the case of failure. set nocount on Always do this after the insert, since it's faster to add the index in bulk than to update the index as you write into the temp table. Since you know the data in this column, you can set the fill factor to 100% to get the best read times. */ Method 2: Temp table without ID In the second approach, we use a temp table without an identity column and simply grab the top row to process, then loop until we find no more rows to process. If you're performing an INSERT/UPDATE/DELETE, again, be sure to use the explicit transactions to vastly reduce the load on your log file by committing per loop, which prevents huge rollbacks in the case of failure. set nocount on Always do this after the insert, since it's faster to add the index in bulk than to update the index as you write into the temp table. Since you know the data in this column, you can set the fill factor to 100% to get the best read times. */ Method 3: Selecting a comma-delimited list of items When most developers/DBAs are asked to come up with a list of comma-delimited values from a table, they typically use a cursor or temp table (as above) to loop through the records. However, if you do not need to use a GROUP BY or an ORDER BY, then you can use the method below that operates in batch to handle the task. This cannot be used with GROUP BY DISTINCT, or ORDER BY, because of how SQL Server handles those operations. Basically, this takes a given variable, and for every row in the table it adds the current value to the variable along with a comma. declare @vrs varchar(4000) This article gives you some good reasons why cursors in SQL Server should be avoided as well as some alternatives that give you looping functionality. Keep in mind that SQL Server is designed around batch processing, so the less you loop, the faster your system will run. |
Tuesday, November 11, 2008
Default trace - A Beginner's Guide
This artical can be found at http://www.sqlservercentral.com/articles/SQL+Server+2005/64547/ - just put here as a reference
Default trace - A Beginner's Guide
By Adam Haines, 2008/11/11
We have all been subject to or know someone who has been in a situation where an object has been altered/created/deleted, without our knowledge, and the application comes to a screeching halt. After fixing the problem, your boss asks you some questions, like what happened, why did it happen, and who did it. SQL Server 2005 introduced a new type of trigger called a DDL trigger that can provide all the answers we need; however, you did not get a chance to implement this functionality. So... what do you do?
Some would tell their boss "I do not know, but I can find out" and then search franticly for 3rd party tools to read the transaction log, hoping for instantaneous salvation. What these few do not know is an answer is silently running in the background. SQL Server 2005 has built in functionality that gives administrators the answers to all these questions.
The answers lie in a new background trace called the default trace. The default trace is exactly what the name specifies, a trace. Default trace is always running in the background of your instance capturing events that administrators can use to troubleshoot problems. The default trace is enabled by default and does not burden the system because it is fairly lightweight. Chances are you had not even noticed this trace running on your instance. To those concerned about overhead, yes there is overhead, but in my mind the benefits far outweigh the minimal overhead. The default trace is not intended to replace DDL trigger functionality and should be used as a means to monitor an SQL Instance, or quickly obtain detailed information about problematic events.
The default trace does not capture all trace events, but captures enough information to become a powerful tool in your toolkit. The default trace captures key information including auditing events, database events, error events, full text events, object creation, object deletion and object alteration. From my experiences and observations on forums, I will be focusing on object level events. It seems that a greater number of people want the "who done it" answer for object DDL events.
The first piece of code is to check the default trace to see if it is enabled.
SELECT * FROM sys.configurations WHERE configuration_id = 1568
If this feature is not available, you will have to configure the advanced option "default trace enabled". Below is the code to enable the trace. Note: you will need the ALTER SETTNGS permission or be in the sysadmin or serveradmin fixed server role to reconfigure.
sp_configure 'show advanced options', 1;
GO
RECONFIGURE;
GO
sp_configure 'default trace enabled', 1;
GO
RECONFIGURE;
GO
The next piece of information we need is the default trace file path, and the function below will return the current trace file. You can grab the initial trace file (log.trc) and rollup every trace file into a single table, but there is a higher overhead associated to bringing more data in. You should use the trace file that best represents the information you are looking for.
Note: the path is defaulted to the \MSSQL\LOG directory, but we can use the function below to get the path
--get the current trace rollover file
SELECT * FROM ::fn_trace_getinfo(0)
Now that we have all the information we need we can get into the trace data. Let's start by creating a new database call TraceDB.
USE [master]
GO
CREATE DATABASE TraceDB
Now open the trace file, as shown below. As you can see, we were able to gather some pretty significant information about who created the database and when the database was created. I have used category id of 5 and a trace_event_id of 46 to filter the data correctly. Event ID 46 represents Object:Created and category 5 is objects. I will provide queries that list all events and categories at the end of this article.
** Make sure to use your trace file path below. Yours may be different than mine.
SELECT
loginname,
loginsid,
spid,
hostname,
applicationname,
servername,
databasename,
objectName,
e.category_id,
cat.name as [CategoryName],
textdata,
starttime,
eventclass,
eventsubclass,--0=begin,1=commit
e.name as EventName
FROM ::fn_trace_gettable('C:\Program Files\Microsoft SQL Server\MSSQL.1\MSSQL\LOG\log.trc',0)
INNER JOIN sys.trace_events e
ON eventclass = trace_event_id
INNER JOIN sys.trace_categories AS cat
ON e.category_id = cat.category_id
WHERE databasename = 'TraceDB' AND
objectname IS NULL AND --filter by objectname
e.category_id = 5 AND --category 5 is objects
e.trace_event_id = 46
--trace_event_id: 46=Create Obj,47=Drop Obj,164=Alter Obj
- You will see more than one entry per object create because these objects have two event sub classes -begin and commit. Each subclass will have an entry.
- You can remove the databasename filter to get object creation events for all databases.
Results (Trimmed for Simplicity):
Now, we have seen what default trace is capable of. Let's create another object and repeat the query. This time around we are going to create a table called "MyTable". Use the following code to create the table.
USE [TraceDB]
GO
CREATE TABLE [dbo].[MyTable](
[id] [int] IDENTITY(1,1) NOT NULL,
[sometext] [char](3) NULL
) ON [PRIMARY]
Now query the default trace using the same query as above. Note you can use the ObjectName column to filter for the specific object you are looking for; otherwise all created database objects are returned.
WHERE databasename = 'TraceDB' AND
objectname = 'MyTable' AND --filter by objectname
e.category_id = 5 AND --category 5 is objects
e.trace_event_id = 46
--trace_event_id: 46=Create Obj,47=Drop Obj,164=Alter Obj
Results (Trimmed for Simplicity):
Let's take the demo a step further by altering MyTable. Issue an alter table statement and add a new column to MyTable, as shown below.
USE [TraceDB]
GO
ALTER TABLE MyTable
ADD col INT
We can now search trace information on the alter event for MyTable. We can use the same query as before but need to make a small modification. You must change the trace_event_id to 164 because event 164 represents the object:Altered event.
WHERE databasename = 'TraceDB' AND
objectname = 'MyTable' AND --filter by objectname
e.category_id = 5 AND --category 5 is objects
e.trace_event_id = 164
--trace_event_id: 46=Create Obj,47=Drop Obj,164=Alter Obj
Results (Trimmed for Simplicity):
Now lets drop MyTable and view the trace details. You must change the trace_event_id to 47 because event 47 represents the object:Deleted event, as shown below.
USE [TraceDB]
GO
DROP TABLE MyTable
We can view trace data by changing the trace_event_id to 47.
WHERE databasename = 'TraceDB' AND
objectname = 'MyTable' AND --filter by objectname
e.category_id = 5 AND --category 5 is objects
e.trace_event_id = 47
--trace_event_id: 46=Create Obj,47=Drop Obj,164=Alter Obj
Results (Trimmed for Simplicity):
As you can see, default trace gives an administrator the ability to find the history of any DDL transaction. I want to point out that default trace is not limited to object DDL history. Among other things, default trace captures log growth events, which can be invaluable to troubleshooting disk capacity problems.
For example, say your log file spontaneous grows enormous. It is important to understand why the log grew spontaneously. No one would argue that one of the first place to look may be SQL Jobs. There are many commands within a job that can potentially cause the log to grow enormous, like reindexing, bulk inserts, bulk deletes etc. By using the trace data you can more easily identify the problem because you can pin-point the exact time the log file began to grow. This greatly reduces the number of possible suspects, which reduces the amount of time required to find the culprit.
The query below will pull all trace data using the log auto growth event. Note: You will not have any log growth for TraceDb because we have not done in large inserts to make the log grow. You should apply this query to another database where you want to monitor log growth.
SELECT
loginname,
loginsid,
spid,
hostname,
applicationname,
servername,
databasename,
objectName,
e.category_id,
cat.name,
textdata,
starttime,
endtime,
duration,
eventclass,
eventsubclass,
e.name as EventName
FROM ::fn_trace_gettable('C:\Program Files\Microsoft SQL Server\MSSQL.1\MSSQL\LOG\log.trc',0)
INNER JOIN sys.trace_events e
ON eventclass = trace_event_id
INNER JOIN sys.trace_categories AS cat
ON e.category_id = cat.category_id
WHERE databasename = 'TraceDB' AND
e.category_id = 2 AND --category 2 is database
e.trace_event_id = 93 --93=Log File Auto Grow
Summary:
The default trace is a valuable tool for the modern DBA's tool belt. It offers a wealth of information, while minimally impacting the system. The default trace is not a widely publicized feature of SQL Server 2005, but is slowly gaining fame. The default trace gives administrators the ability to get detailed information about auditing events, database events, error events, full text events, object creation, object deletion and object alteration events. With this much information at their fingertips, administrators are more productive and can more easily identify problems in a production environment. My recommendations are to look through the events and see what information already exists for your instances. Default trace should not only be used reactively but proactively. A proactive mentality will reveal small problems before they escalate to bigger problems.
Event and Category Queries
--list of events
SELECT *
FROM sys.trace_events
--list of categories
SELECT *
FROM sys.trace_categories
--list of subclass values
SELECT *
FROM sys.trace_subclass_values
--Get trace Event Columns
SELECT
t.EventID,
t.ColumnID,
e.name AS Event_Descr,
c.name AS Column_Descr
FROM ::fn_trace_geteventinfo(1) t
INNER JOIN sys.trace_events e
ON t.eventID = e.trace_event_id
INNER JOIN sys.trace_columns c
ON t.columnid = c.trace_column_id
References:
List of available events:
http://blogs.technet.com/vipulshah/archive/2007/04/16/default-trace-in-sql-server-2005.aspx
How to enable default trace:
http://msdn.microsoft.com/en-us/library/ms175513(SQL.90).aspx
By Adam Haines, 2008/11/11
Thursday, November 6, 2008
Reporting Services Adding VB code / Getting user login whilst still allowing subscriptions
Here is a work around using a custom code function.
If you have really complex tasks - or ones like our problem - then VB code can be embedded in your report server report.
- In Design view, right-click the design surface outside the border of the report and click Report Properties.
- Click Code.
- In Custom code, type the code.
- Public Function UserName()
Try
Return Report.User!UserID
Catch
Return "System"
End Try
End Function
Now we need to make the user name available as a parameter in the report so we can use it in our underlying SQL.
- Click on the Report Menu -> Parameters
- Add a new parameter
- In the default values use a non queried value of =Code.UserName() to call the custom code we entered above.
- This particular parameter is needed to determine the list of Market parameters used in this report. It needs to be moved (using up and down arrows) above any parameters dependant on it - in this case Mkt.
The @UserName parameter is now available for us to build our SQL in the data section of the report.
Tuesday, November 4, 2008
VB Script to Kill and Restart a running process
' VBScript to kill a running program, pause for iDelay seconds then restart
' Demonstrates working with winmgmts, timer and shell
' On NT4 boxes this will require Windows Management Instrumentation to be installed
' http://www.microsoft.com/downloads/details.aspx?FamilyID=c174cfb1-ef67-471d-9277-4c2b1014a31e&displaylang=en
' ------------------------ -------------------------------'
Option Explicit
Dim oWMIService, oProcess, colProcess, oShell
Dim intErrNum
Dim strComputer, strProcessKill, strProcessFullPath, iDelay
'set Machine/Process variables here
strComputer = "Machine_Name"
strProcessKill = "wordpad.exe"
strProcessFullPath = """C:\Program Files\Windows NT\Accessories\wordpad.exe"""'Path has
spaces - needs to be sent as qutoed
'check for WMI - use WMI to connect to the registry
On Error Resume Next
Dim oReg : Set oReg = GetObject("winmgmts:root\default:StdRegProv")
intErrNum = Err.Number
On Error Goto 0
Err.Clear
'WMI connection error
If intErrNum <> 0 Then
MsgBox "This script requires " & Chr(34) & "WMI" & Chr(34) &_
", Windows Management Instrumentation, to run.", vbOKCancel + vbExclamation,"WMI Not
Installed!"
WScript.Quit
End If 'WMI execution error
iDelay = 30'30 second delay before restart'
'locate and kill the process
Set oWMIService = GetObject("winmgmts:" _
& "{impersonationLevel=impersonate}!\\" _
& strComputer & "\root\cimv2")
Set colProcess = oWMIService.ExecQuery ("Select * from Win32_Process" )
For Each oProcess in colProcess
if lcase(oProcess.Name) = lcase(strProcessKill) then
oProcess.Terminate()
'WSCript.Echo "Just killed process " & strProcessKill & " on " & strComputer
end if
Next
'pause for set delay
'WSCript.Echo "Pausing"
WScript.Sleep(iDelay*1000)
'WSCript.Echo "Restarting"
'run program
Set oShell = WScript.CreateObject("WScript.Shell")
oShell.run(strProcessFullPath)
Set oShell = Nothing
Set colProcess = Nothing
Set oWMIService = Nothing
WScript.Quit
Monday, November 3, 2008
OS - Getting back server disk space
Unaccounted couple of gig missing?
1. This can be your pagefile.sys (virtual memory) You can move it to another disk or - for a performance increase - split it across multiple disks (if they are on separate spindles) - there is a good article on this at http://members.shaw.ca/bsanders/WindowsGeneralWeb/RAMVirtualMemoryPageFileEtc.htm
- In Explorer go to Tools -> Options -> View and make sure "Hide protected OS files" is unchecked and "Show Hidden files" is selected
- Look in your c:\ directory and you can see the system files
- Go to My Computer -> Properties -> Advanced Tab ->Performance options -> Virtual Memory
- Change the size and location of the virtual memory
Log Files
Windows log files are located C:\WINNT\system32\LogFiles. Clear out all but the last month