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MS SQL

Posted Mar 12, 2001

Useful Undocumented Extended Stored Procedures

By Alexander Chigrik


Introduction

Extended stored procedure is a dynamic link library that run directly in the address space of SQL Server and is programmed using the SQL Server Open Data Services API. You can write your own extended stored procedure in a programming language such as C. You can run extended stored procedures from the Query Analyzer, for example, as normal stored procedures. Extended stored procedures are used to extend the capabilities of SQL Server.

In this article, I want to tell you about some useful undocumented extended stored procedures. The extended stored procedures, which were described below, are working with SQL Server 7.0 as well as with SQL Server 2000.

sp_MSgetversion

This extended stored procedure can be used to get the current version of Microsoft SQL Server. To get the current SQL Server version, run
EXEC master..sp_MSgetversion
Note. By the way, more recommended way to get the current SQL Server version (this way provides more information) is executing the following select statement:
select @@version

xp_dirtree

This extended stored procedure can be used to get the list of all subdirectories for the passed directory. To get all subdirectories for the C:\MSSQL7 directory, run
EXEC master..xp_dirtree 'C:\MSSQL7'
Here is the result set from my machine:
subdirectory  depth
------------- -----------
Binn            1
Resources       2
1033            3
DevTools        1
Include         2
Lib             2
Data            1
Install         1
HTML            1
Books           1
LOG             1
JOBS            1
BACKUP          1
REPLDATA        1
FTP             2

xp_enum_oledb_providers

This extended stored procedure can be used to get the list of all OLE DB providers. The xp_enum_oledb_providers returns Provider Name, Parse Name and Provider Description. To get the list of all OLE DB providers, run
EXEC master..xp_enum_oledb_providers

xp_enumcodepages

This extended stored procedure can be used to get the list of all code pages, character sets and their description. This is the example:
EXEC master..xp_enumcodepages

xp_enumdsn

This extended stored procedure returns the list of all System DSNs and their description. To get the list of System DSNs, run:
EXEC master..xp_enumdsn

xp_enumerrorlogs

This extended stored procedure returns the list of all error logs with the last change date. To get the list of error logs, run:
EXEC master..xp_enumerrorlogs
Here is the result set from my machine:
Archive #   Date
----------- ------------------
6           02/27/2001  08:00
5           03/04/2001  22:46
4           03/05/2001  22:28
3           03/08/2001  10:32
2           03/10/2001  00:06
1           03/10/2001  23:29
0           03/11/2001  18:58

xp_enumgroups

This extended stored procedure returns the list of Windows NT groups and their description. To get the list of the Windows NT groups, run:
EXEC master..xp_enumgroups

xp_fileexist

You can use this extended stored procedure to determine whether the particular file exists on the disk or not. Syntax:
EXECUTE xp_fileexist filename [, file_exists INT OUTPUT]
To check whether the file boot.ini exists on the disk c: or not, run:
EXEC master..xp_fileexist 'c:\boot.ini'
Here is the result set from my machine:
File Exists File is a Directory Parent Directory Exists
----------- ------------------- -----------------------
1           0                   1

xp_fixeddrives

This very useful extended stored procedure returns the list of all fixed hard drives and the amount free space in Mb for each hard drive. This is the example:
EXEC master..xp_fixeddrives
Here is the result set from my machine:
drive MB free
----- -----------
C     12082
D     396
E     793
F     46

xp_getnetname

This extended stored procedure returns the WINS name of the SQL Server that you're connected to. This is the example:
EXEC master..xp_getnetname
Here is the result set from my machine:
Server Net Name
---------------
CHIGRIK

xp_readerrorlog

This extended stored procedure returns the content of the errorlog file. You can find this errorlog file in the C:\MSSQL7\Log directory, by default. To see the text of the errorlog file, run:
EXEC master..xp_readerrorlog

xp_regdeletekey

This extended stored procedure will delete the whole key from the registry. You should use it very carefully. Syntax:
EXECUTE xp_regdeletekey [@rootkey=]'rootkey',
                        [@key=]'key'
To delete key 'SOFTWARE\Test' from the 'HKEY_LOCAL_MACHINE', run:
EXEC master..xp_regdeletekey
     @rootkey='HKEY_LOCAL_MACHINE',
     @key='SOFTWARE\Test'

xp_regdeletevalue

This extended stored procedure will delete the particular value for the key from the registry. You should use it very carefully. Syntax:
EXECUTE xp_regdeletevalue [@rootkey=]'rootkey',
                          [@key=]'key',
                          [@value_name=]'value_name'
To delete value 'TestValue' for the key 'SOFTWARE\Test' from the 'HKEY_LOCAL_MACHINE', run:
EXEC master..xp_regdeletevalue
     @rootkey='HKEY_LOCAL_MACHINE',
     @key='SOFTWARE\Test',
     @value_name='TestValue'

xp_regread

This extended stored procedure is used to read from the registry. Syntax:
EXECUTE xp_regread [@rootkey=]'rootkey',
                   [@key=]'key'
                   [, [@value_name=]'value_name']
                   [, [@value=]@value OUTPUT]
To read into variable @test from the value 'TestValue' from the key 'SOFTWARE\Test' from the 'HKEY_LOCAL_MACHINE', run:
DECLARE @test varchar(20)
EXEC master..xp_regread @rootkey='HKEY_LOCAL_MACHINE',
  @key='SOFTWARE\Test',
  @value_name='TestValue',
  @value=@test OUTPUT
SELECT @test
Here is the result set from my machine:
--------------------
Test

xp_regwrite

This extended stored procedure is used to write in the registry. Syntax:
EXECUTE xp_regwrite [@rootkey=]'rootkey',
                    [@key=]'key',
                    [@value_name=]'value_name',
                    [@type=]'type',
                    [@value=]'value'
To write the variable 'Test' in value 'TestValue', key 'SOFTWARE\Test', 'HKEY_LOCAL_MACHINE', run:
EXEC master..xp_regwrite
     @rootkey='HKEY_LOCAL_MACHINE',
     @key='SOFTWARE\Test',
     @value_name='TestValue',
     @type='REG_SZ',
     @value='Test'

xp_subdirs

This extended stored procedure is used to get the list of subdirectories for the passed directory. In comparison with xp_dirtree, xp_subdirs returns only those directories whose depth = 1. This is the example:
EXEC master..xp_subdirs 'C:\MSSQL7'
Here is the result set from my machine:
subdirectory
-----------------------
Binn
DevTools
Data
Install
HTML
Books
LOG
JOBS
BACKUP
REPLDATA


» See All Articles by Columnist Alexander Chigrik




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