how to create a global variable in sql server 2008 - sql-server-2008

Question

I have a view that returns users projects and also their windows login. An example of the data is below:
project | Login
------------------
project 1 | richab
project 2 | stevej
I need to append the domain to the login. I could put this in the code but i dont want to do that in every view I ever create that pulls users logins.
Can I create a global variable that I can reference in the views code. How can I achieve this? What's best practice for this?

Answer 1

I don't know if the SQL Server has global variables, but you can use a user defined function as follows:
CREATE FUNCTION dbo.fn_GetDomainName()
RETURNS STRING
AS
BEGIN
RETURN 'domain_name\\'
END
and do a SELECT dbo.fn_GetDomainName() + Login FROM table WHERE ... at the corresponding locations in your views.

Answer 2

There's no such thing as a global variable in SQL Server.
You can't just do:
DECLARE ##GlobalVar int
You can fake it with CONTEXT_INFO but to use something that would last beyond a session or restart you need to do something like this:
USE master
IF OBJECT_ID('dbo.sp_GlobalVariables') IS NOT NULL
DROP TABLE dbo.sp_GlobalVariables
GO
CREATE TABLE dbo.sp_GlobalVariables
(
varName NVARCHAR(100) COLLATE Latin1_General_CS_AI,
varValue SQL_VARIANT
)
GO
IF OBJECT_ID('dbo.sp_GetGlobalVariableValue') IS NOT NULL
DROP PROC dbo.sp_GetGlobalVariableValue
GO
CREATE PROC dbo.sp_GetGlobalVariableValue
(
#varName NVARCHAR(100),
#varValue SQL_VARIANT = NULL OUTPUT
)
AS
SET NOCOUNT ON
-- set the output parameter
SELECT #varValue = varValue
FROM sp_globalVariables
WHERE varName = #varName
-- also return it as a resultset
SELECT varName, varValue
FROM sp_globalVariables
WHERE varName = #varName
SET NOCOUNT OFF
GO
IF OBJECT_ID('dbo.sp_SetGlobalVariableValue') IS NOT NULL
DROP PROC dbo.sp_SetGlobalVariableValue
GO
CREATE PROC dbo.sp_SetGlobalVariableValue
(
#varName NVARCHAR(100),
#varValue SQL_VARIANT,
#result CHAR(1) = NULL OUTPUT
)
AS
SET NOCOUNT ON
UPDATE dbo.sp_GlobalVariables
SET varValue = #varValue
WHERE varName = #varName;
-- if it doesn't exist yet add it
IF ##rowcount = 0
BEGIN
INSERT INTO dbo.sp_GlobalVariables(varName, varValue)
SELECT #varName, #varValue
-- return it as inserted
SELECT #result = 'I'
END
-- return it as updated
SELECT #result = 'U'
SET NOCOUNT OFF
GO
DECLARE #dt DATETIME
SELECT #dt = GETDATE()
EXEC sp_SetGlobalVariableValue 'GlobalDate', #dt;
EXEC sp_SetGlobalVariableValue 'GlobalInt', 5;
EXEC sp_SetGlobalVariableValue 'GlobalVarchar', 'This is a very good global variable'
EXEC sp_SetGlobalVariableValue 'GlobalBinary', 0x0012314;
GO
EXEC sp_GetGlobalVariableValue 'GlobalDate'
EXEC sp_GetGlobalVariableValue 'GlobalInt'
EXEC sp_GetGlobalVariableValue 'GlobalVarchar'
EXEC sp_GetGlobalVariableValue 'GlobalBinary'
GO
-- update value in master
EXEC sp_SetGlobalVariableValue 'GlobalVarchar', 'New varchar value'
USE AdventureWorks
EXEC sp_GetGlobalVariableValue 'GlobalDate'
EXEC sp_GetGlobalVariableValue 'GlobalInt'
EXEC sp_GetGlobalVariableValue 'GlobalVarchar'
EXEC sp_GetGlobalVariableValue 'GlobalBinary'
-- update value in AdventureWorks
EXEC sp_SetGlobalVariableValue 'GlobalInt', 6
EXEC sp_GetGlobalVariableValue 'GlobalDate'
EXEC sp_GetGlobalVariableValue 'GlobalInt'
EXEC sp_GetGlobalVariableValue 'GlobalVarchar'
EXEC sp_GetGlobalVariableValue 'GlobalBinary'

Answer 3

You can use a temp table.
My scenario is that when data is updated via a known process, it adds a note to the audit table stating that 'this was done on purpose'.
When that proc fires, it inserts a single value into #auditnote (which is a temp table I create on the fly).
The trigger checks for that table. If it exists, it pulls off the note and puts it on the audit table.
If it doesn't, then it goes about it's business.
I looked at using an ## variable, but the trick there is determining if the variable exists. I don't see a way.
EXAMPLE:
Stored Procedure:
SELECT 'Alrighty Then' AS NOTE INTO #AuditNote
Trigger:
DECLARE #noteExists BIT
DECLARE #note NVARCHAR(500)
IF OBJECT_ID('tempdb..#auditnote') IS NOT NULL
BEGIN
SELECT
TOP (1)
#noteExists = 1,
#note = Note
FROM
#auditNote
END ELSE BEGIN
SELECT #noteExists = 0
END
-- do something with the note
IF #noteExists = 1
BEGIN
DROP TABLE #AuditNotes
END
I'm using #noteExists rather than a null check because someone could insert a null as the note, so we don't know if null means TABLE DOESN'T EXIST or NOTE IS NULL.