How do I drop table variables in SQL-Server? Should I even do this?

问题

I have a table variable in a script (not a stored procedure). Two questions:

How do I drop the table variable? Drop Table @varName gives an "Incorrect snytax" error.
Should I always do this? I hear it's a good practice. Is it ever really necessary for small scripts like this?

Here's my code:

Declare @projectList table(
    name varchar(40) NOT NULL);

Insert Into @projectList
Values ('BCR-00021')

Select *
From @projectList

Drop Table @projectList -- does not work

回答1:

Table variables are automatically local and automatically dropped -- you don't have to worry about it.

回答2:

Table variables are just like int or varchar variables.

You don't need to drop them. They have the same scope rules as int or varchar variables

The scope of a variable is the range of Transact-SQL statements that can reference the variable. The scope of a variable lasts from the point it is declared until the end of the batch or stored procedure in which it is declared.

回答3:

if somebody else comes across this... and you really need to drop it like while in a loop, you can just delete all from the table variable:

DELETE FROM @tableVariableName

回答4:

But you all forgot to mention, that if a variable table is used within a loop it will need emptying (delete @table) prior to loading with data again within a loop.

回答5:

Just Like TempTables, a local table variable is also created in TempDB. The scope of table variable is the batch, stored procedure and statement block in which it is declared. They can be passed as parameters between procedures. They are automatically dropped when you close that session on which you create them.

回答6:

Here is a solution

Declare @tablename varchar(20)
DECLARE @SQL NVARCHAR(MAX)

SET @tablename = '_RJ_TEMPOV4'
SET @SQL = 'DROP TABLE dbo.' + QUOTENAME(@tablename) + '';

IF  EXISTS (SELECT * FROM sys.objects WHERE object_id = OBJECT_ID(@tablename) AND type in (N'U'))
    EXEC sp_executesql @SQL;

Works fine on SQL Server 2014 Christophe

来源：https://stackoverflow.com/questions/5653520/how-do-i-drop-table-variables-in-sql-server-should-i-even-do-this

标签

sql

sql-server

table-variable