Question

I’m after a simple stored procedure to drop tables. Here’s my first attempt:

CREATE PROC bsp_susf_DeleteTable (@TableName char)
AS
IF EXISTS (SELECT name FROM sysobjects WHERE name = @TableName)
BEGIN
DROP TABLE @TableName
END

When I parse this in MS Query Analyser I get the following error:

Server: Msg 170, Level 15, State 1, Procedure bsp_susf_DeleteTable, Line 6
Line 6: Incorrect syntax near '@TableName'.

Which kind of makes sense because the normal SQL for a single table would be:

IF EXISTS (SELECT name FROM sysobjects WHERE name = 'tbl_XYZ')
BEGIN
    DROP TABLE tbl_XYZ
END

Note the first instance of tbl_XYZ (in the WHERE clause) has single quotes around it, while the second instance in the DROP statement does not. If I use a variable (@TableName) then I don’t get to make this distinction.

So can a stored procedure be created to do this? Or do I have to copy the IF EXISTS … everywhere?

Answer 1

You should be able to use dynamic sql:

declare @sql varchar(max)
if exists (select name from sysobjects where name = @TableName)
BEGIN
   set @sql = 'drop table ' + @TableName
   exec(@sql)
END

Hope this helps.

Update: Yes, you could make @sql smaller, this was just a quick example. Also note other comments about SQL Injection Attacks