How to check existence of a sql server object and drop it?

Question

EDIT: the function creation was missing, sorry about that

I have a T-SQL request that goes:

DECLARE @IsSomething bit
SET @IsSomething = 0
IF /some tests/ SET @IsSomething = 1
EXEC('
CREATE FUNCTION IsSomething ()
RETURNS bit
AS
BEGIN
    RETURN ' + @IsSomething + '
END')

Of course if I run it twice I get

There is already an object named 'IsSomething ' in the database.

How would I do something like this:

IF EXIST @IsSomething DESTROY @IsSomething // (Pseudo bad code)

Thanks!

Answer 1

Seems analogous to any other language where you try to declare the same global variable multiple times. Normally we don't write:

var a;
a = 0;
...
...
undefine a;
a = 1;
...
...
undefine a;
a = 2;

Seems to me like you just need to be aware of the structure of the code you are writing.

I wouldn't consider a declared variable to be a "database object", BTW. But your question makes more sense if for some reason you do.

Answer 2

IF EXISTS (SELECT * FROM dbo.sysobjects WHERE id = object_id (N'[dbo].[IsSomething]') AND OBJECTPROPERTY(id, N'IsFunction') = 1) 

DROP function IsSomething
GO

Answer 3

Like this

IF OBJECT_ID('YourObject', 'ObjectsType') IS NOT NULL DROP <ObjectsType> [YourObject]

Answer 4

The answer to your edited question is:

if object_id('IsSomething', 'fn') is not null drop function IsSomething
go

Answer 5

The template, from Visual Studio 2008 Add -> Stored Procedure Script is

IF EXISTS (SELECT * FROM sysobjects WHERE type = 'P' AND name = 'Stored_Procedure_Name')
    BEGIN
     DROP  Procedure  Stored_Procedure_Name
    END

GO

CREATE Procedure Stored_Procedure_Name
/*
    (
     @parameter1 int = 5,
     @parameter2 datatype OUTPUT
    )

*/
AS


GO

/*
GRANT EXEC ON Stored_Procedure_Name TO PUBLIC

GO
*/

For a Procedure, Sql Server Management Studio gives the following script to drop

IF  EXISTS (SELECT * FROM sys.objects WHERE object_id = OBJECT_ID(N'[dbo].[usp_DeleteXyz]') AND type in (N'P', N'PC'))
DROP PROCEDURE [dbo].[usp_DeleteXyz]

likewise for a Function it's generated script is

IF  EXISTS (SELECT * FROM sys.objects WHERE object_id = OBJECT_ID(N'[dbo].[udf_GetXyz]') AND type in (N'FN', N'IF', N'TF', N'FS', N'FT'))
DROP FUNCTION [dbo].[udf_GetXyz]

I've mostly seen the latter forms (2-line versions) in most codebases I've worked on, and there's no need to declare a variable.