is it Possible to set variable inside a View in Sql Server? - sql

Question

I want to set a variable in Sql Server that is selecting date from a view the query I am using is
declare #var varchar(20)
set #var = (SELECT Current_Period_SID FROM dbo.VW_Current_Period_SID_USNT)
just wondering is there a way to set variable in a view something like
CREATE VIEW mp_test AS
declare #var varchar(20)
set #var = (SELECT Current_Period_SID FROM dbo.VW_Current_Period_SID_USNT)
GO
Doing this gives Error

Answer 1

No. You can't do that in a view. I'm not even sure what the point of the above view would be since it doesn't return any value. Even if you could, you wouldn't want to. A variable like this can only store one varchar(20) value. Without an "order by" and top statement you would either get an error or a non-deterministic value unless your table happens to only have a single record.

Answer 2

You can easily fake a variable in your view using CTE. You can test-run it in your version of SQL Server.
CREATE VIEW vwImportant_Users AS
WITH params AS (
SELECT
varType='%Admin%',
varMinStatus=1)
SELECT status, name
FROM sys.sysusers, params
WHERE status > varMinStatus OR name LIKE varType
SELECT * FROM vwImportant_Users
yielding output:
status name
12 dbo
0 db_accessadmin
0 db_securityadmin
0 db_ddladmin
also via JOIN
WITH params AS ( SELECT varType='%Admin%', varMinStatus=1)
SELECT status, name
FROM sys.sysusers INNER JOIN params ON 1=1
WHERE status > varMinStatus OR name LIKE varType
also via CROSS APPLY
WITH params AS ( SELECT varType='%Admin%', varMinStatus=1)
SELECT status, name
FROM sys.sysusers CROSS APPLY params
WHERE status > varMinStatus OR name LIKE varType