Monday, June 07, 2004

Registry manipulation from SQL

Registry Manupulation from SQL Server is pretty easy. There are 4 extended stored procedure in SQL Server 2000 for the purpose of manupulating the server registry. They are:

1) xp_regwrite
2) xp_regread
3) xp_regdeletekey
4) xp_regdeletevalue

Let us see each one of them in detail!

About xp_regwrite

This extended stored procedure helps us to create data item in the (server’s) registry and we could also create a new key.

Usage:

We must specify the root key with the @rootkey parameter and an individual key with the @key parameter. Please note that if the key doesn’t exist (without any warnnig) it would be created in the registry. The @value_name parameter designates the data item and the @type the type of the data item. Valid data item types include REG_SZ and REG_DWORD. The last parameter is the @value parameter, which assigns a value to the data item.

Let us now see an example which would add a new key called "TestKey", and a new data item under it called TestKeyValue:

Use Master
Go


xp_regwrite
@rootkey='HKEY_LOCAL_MACHINE',
@key='SOFTWARE\Vadivel\RegistryExample\thinkingMS\TestKey',
@value_name='TestKeyValue',
@type='REG_SZ', @value='Test'


About xp_regread

This extended stored procedure reads an individual registry key (OR) to read a data item in the key. The @rootkey parameter is the root key in the registry, and the @key parameter is the individual key.

Usage: We must specify the registry key’s root and key as shown below:

Use Master
Go
xp_regread
@rootkey='HKEY_LOCAL_MACHINE',
@key='SOFTWARE\Vadivel\RegistryExample\thinkingMS\'

As we are using @rootkey and @key alone it would test the existence of the key only. i.e., if the key exist it would return 1, if not it would return 0. To fetch the value stored inside the key (which we did it using xp_regwrite) use the below code snippet:

Use Master
Go


Exec xp_regread
@rootkey='HKEY_LOCAL_MACHINE',
@key='SOFTWARE\Vadivel\RegistryExample\thinkingMS\TestKey',
@value_name='TestKeyValue'


Assume that you have installed SQL Server in your machine and unfortunately you lost the CD Key. Won't it be useful if there is a means by which you could retrieve the CD Key used while installing? Obviously Yes right :) Execute the below script to fetch the CD KEY.

USE master
Go


EXEC xp_regread
@rootkey = 'HKEY_LOCAL_MACHINE',
@key = 'SOFTWARE\Microsoft\Microsoft SQL Server\80\registration',
@value_name = 'CD_KEY'


About xp_regdeletekey

As the name say, this procedure allows us to delete a key from your registry. For your information this won't warn us before the procedure deletes the entire key.

Usage: Use the @rootkey parameter to specify the root registry key and @key parameter to tell which key you want to delete:

Use Master
Go


xp_regdeletekey
@rootkey='HKEY_LOCAL_MACHINE',
@key='SOFTWARE\Vadivel\RegistryExample\thinkingMS\TestKey'


About xp_regdeletevalue

You can also delete individual data items inside a registry key by using the xp_regdeletevalue procedure. The procedure uses the same parameters as the xp_regdeletekey procedure, but has an added @value_name parameter, which is the data item name:

Use Master
Go


xp_regdeletevalue
@rootkey='HKEY_LOCAL_MACHINE',
@key='SOFTWARE\Vadivel\RegistryExample\thinkingMS\TestKey',
@value_name='TestKeyValue'


Points to Note:

1. You can replace the first 3 lines in the code snippet with master..

2. After running the scripts for testing go to START >> RUN >> And type regedit. This would open up the registry editor. Navigate to HKEY_LOCAL_MACHINE\SOFTWARE to find the rest we discussed above.

3. Once done run the below scripts to clear the entries we added to the registry

---Run this to Delete "TestKey" entry
xp_regdeletekey
@rootkey='HKEY_LOCAL_MACHINE',
@key='SOFTWARE\Vadivel\RegistryExample\thinkingMS\TestKey'


---Run this to Delete "thinkingMS" entry
xp_regdeletekey
@rootkey='HKEY_LOCAL_MACHINE',
@key='SOFTWARE\Vadivel\RegistryExample\thinkingMS'

---Run this to Delete "RegistryExample" entry
xp_regdeletekey
@rootkey='HKEY_LOCAL_MACHINE',
@key='SOFTWARE\Vadivel\RegistryExample'

---Run this to Delete "Vadivel" entry
xp_regdeletekey
@rootkey='HKEY_LOCAL_MACHINE',
@key='SOFTWARE\Vadivel'

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