SQL Server / Create view from stored procedure - sql-server

Question

I am trying to create a view out of a stored procedure and am perplexed to see two opposing results from a very similar approach.
Example 1
CREATE PROCEDURE cv AS
GO
DECLARE #sql nvarchar(MAX)
SET #sql = 'CREATE VIEW test AS SELECT * FROM someOtherTable'
exec (#sql)
Whereas this example creates the view once the procedure is created for the 1st time, it will not recreate the view when I execute the procedure at a later stage using:
EXEC cv
Example 2
CREATE PROCEDURE cv
#table SYSNAME
AS
DECLARE #sql nvarchar(MAX)
SET #sql = 'CREATE VIEW '+ #table +' AS SELECT * FROM someOtherTable'
This one instead does not create the view when the procedure is created for the first time but creates the view afterwards every time it is called by:
EXEC #sql;
Why is this the case? I think this is really confusing and does not make sense or does it?

Answer 1

For your 1st statement
CREATE PROCEDURE cv AS
GO --<-- This GO here terminates the batch
DECLARE #sql nvarchar(MAX)
SET #sql = 'CREATE VIEW test AS SELECT * FROM someOtherTable'
exec (#sql)
the GO batch terminator create the procedure and the EXECUTES the following statement straightaway. So it appears to you as you have created a procedure which created the view for you.
Infact these are two statements in two batches.
--BATCH 1
CREATE PROCEDURE cv AS
GO
--BATCH 2
DECLARE #sql nvarchar(MAX)
SET #sql = 'CREATE VIEW test AS SELECT * FROM someOtherTable'
exec (#sql)
Batch 1 Creates a procedure which has nothing inside it, but it creates a procedure object for you with no functionality/Definition at all.
Statement after the key word GO is executed separately and creates the view for you.
My Suggestion
Always check for an object's existence before you create it. I would write the procedure something like this..
CREATE PROCEDURE cv
AS
BEGIN
SET NOCOUNT ON;
IF OBJECT_ID ('test', 'V') IS NOT NULL
BEGIN
DROP VIEW test
END
DECLARE #sql nvarchar(MAX)
SET #sql = 'CREATE VIEW test AS SELECT * FROM someOtherTable'
exec (#sql)
END

Answer 2

In Example 1 - you are creating a view with a hard-coded name of test. On subsequent runs of your proc, as the view already exists, SQL Server will throw an error because you are trying to create a view with the same name as one that already exists.
In Example 2, you are passing in the name of the view as a parameter. This will always create a new view unless the #table value you pass in corresponds to an existing view.
Just wondering - why are you creating a view with a stored proc? This is not something you would normally do in SQL.

Answer 3

You need to change
EXEC #sql to EXEC (sql)
EXEC can be use to run stored procedure, not dynamic sql
eg.
declare #dd varchar(100)='Select ''A'''
exec (#dd) ->will work fine
exec #dd -> Error
Read more about The Curse and Blessings of Dynamic SQL

Answer 4

Create view statement cannot be used with a stored procedure

Answer 5

EXEC ('CREATE VIEW ViewName AS SELECT * FROM OPENQUERY(Yourservername,''EXECUTE [databasename].[dbo].[sp_name] ''''' +Parameter + ''''''')')