SQL-DMO (Distributed
Management Objects) provides a programmatic (COM) interface to SQL Server.
Its a great tool for automating routine tasks – far more flexible than
T-SQL in most cases. In this article I’ll demonstrate several uses of DMO that
will give you a starting point for building your own solutions. I’ll be using
VB Script for these examples, but you can use any language that supports COM.
Code has been tested on SQL 2000, but should work fine in SQL 7.
my DMO scripts, then convert to VB Script. If you use this method, a few things
to remember:
-
Set a reference to Microsoft SQL-DMO so
you get Intellisense
-
Use CreateObject instead of New when
creating your objects- VB Script doesnt support New
-
Use the variant model functions (CHR,
UCASE, etc) instead of the ones optimized for strings (CHR$,UCASE$) – VB
Script doesnt support the string versions
-
Convert constants to their actual values
-
Remove all data typing. A handy trick is
to just comment out the type declaration, so you can more easily read the code
and you can always uncomment them if you dump the code back into VB to make
changes.
If youre just using
Notepad to write your scripts, add a few lines at a time and test. Use Msgbox to
help you debug and trace your program flow. Scripts should be saved with the
standard .VBS extension – you can execute them by double clicking.
Example #1 – How many
databases do you have?
This shows how to connect
to SQL running on your local machine, display the number of databases, then
disconnect.
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Dim oServer ‘get a reference to the DMO object Set oServer = ‘use a trusted connection oServer.LoginSecure = True oServer.Connect ‘this displays the count – should be the ‘select count(*) from master..sysdatabases MsgBox oServer.Databases.Count ‘always clean up when youre done oServer.DisConnect Set oServer = Nothing |
Example #2 – How much
space is available in each database?
This script cycles through
each database and returns the free space in megabytes. Note that this time Im
specifying the server to connect to rather than relying on the default behavior
of connecting to the local machine.
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Dim oServer Dim oDatabase Dim sResults Set oServer = oServer.LoginSecure = True ‘this time Im specifying which server to oServer.Connect "Andy" ‘this will return the name of each database ‘space in megabytes. The Chr(9) is a tab, ‘to carriage return and line feed For Each oDatabase In oServer.Databases Next ‘show the answer – could easily send using MsgBox sResults oServer.DisConnect Set oServer = Nothing |
Example #3 – Update Statistics if Auto Update is Disabled
You arent restricted to
just reading information, you can make changes or take action as well. In this
example Im going to update the statistics for any database that has the auto
update option disabled. At the end Im adding some additional text to the
sResult variable to make the display a little more informative.
|
Dim oServer Dim oDatabase Dim sResults Set oServer = oServer.LoginSecure = True ‘this time Im specifying which server to oServer.Connect "Andy" ‘if auto update stats is turned off, update ‘databases For Each oDatabase In oServer.Databases If oDatabase.DBOption.AutoUpdateStat = False Then End If Next ‘here Im making the output a little fancier If sResults <> "" Then sResults = "Statistics were updated for the following databases: Else sResults = "No databases had auto update statistics turned End If MsgBox sResults oServer.DisConnect Set oServer = Nothing |
Example #4 – Backup All Databases
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Dim oServer Dim oDatabase Dim oBackup Dim sBAKFilePath ‘change this to where ever you want ‘backslash, we add it below sBAKFilePath = "C:Backup" ‘we need a backup object in addition Set oServer = Set oBackup = oServer.LoginSecure = True oServer.Connect "(local)" ‘this will do a full backup of every ‘device For Each oDatabase In If End If Next ‘clean up Set oBackup = Nothing oServer.DisConnect Set oServer = Nothing |
Deploying Your Scripts
Once youve gotten your
code to work successfully, there are several ways to put it to work:
-
Leave it in a VBS file (or
compile into an executable) to be run manually on as needed basis. -
Add it as a step to SQL job –
select ActiveX Script as the step type. Keep in mind that the size of the step
is limited to about 3200 chars (the size of the command column in sysjobsteps). -
Schedule the VBS/EXE to run as a
OS scheduled task or as a SQL job of type CmdExec.
If you play to run your
code on the server, comment out or remove any lines that use Msgbox, otherwise
your script will be stalled waiting on the user to click OK. Even worse, if you
run the script as a SQL Agent ActiveX Script job, the message box will be
suppressed so the server operator cannot see it, but the job will still be
waiting on user input.
One other technique you
may find useful is to include Print statements in your script. These will
fail when you test your script in VB or VB Script, but when run under SQL Agent
the output of the print statement will be entered into the job history. Example
#1 might be modified as follows:
Replace
MsgBox
oServer.Databases.Count
With
Print
“Count=” & oServer.databases.count
References
Books
Online has an object model diagram that is very useful (search for ‘SQL-DMO,
object tree in SQL 2000). You can also find some useful articles at www.devx.com
and SQL Server Magazine.
