Using a table variable inside of a exists statemen

问题:

I am trying to update a column inside of a table variable based on a condition, the condition being that the ID of the table variable does not exist in a different table:

DECLARE @BugRep TABLE(BugCode VARCHAR(50),DevFirstName VARCHAR(50), DevLastName    VARCHAR(50), BugDate VARCHAR(20), IsValid VARCHAR(1))

UPDATE @BugRep 
SET IsValid = 'N' WHERE NOT EXISTS(SELECT * FROM BUG b WHERE @BugRep.BUGCODE = b.CODE)

When i try to compile the procedure that has these statements, I get a "Must declare the scalar variable "@BugRep" message.

How do i go about using the table variable inside of the NOT EXISTS clause?

I am using SQL Server 2008

回答1:

This will work:

[@BugRep].BUGCODE

You'll also need to change "b.CODE" to "b.BUGCODE" by the way ;)

回答2:

This is actually very picky. Check out the in-line comments below using womp's suggestion and also trying a LEFT OUTER JOIN.

CREATE TABLE Bug (CODE VARCHAR(50))

DECLARE @BugRep TABLE (
    BugCode         VARCHAR(50),
    --DevFirstName    VARCHAR(50),
    --DevLastName     VARCHAR(50),
    --BugDate         VARCHAR(20),
    IsValid         CHAR(1)
)

INSERT INTO Bug (CODE) VALUES ('Code1'), ('Code2'), ('Code3')

INSERT INTO @BugRep (BugCode) VALUES ('Code1'), ('Code2'), ('Code4')

SELECT CODE FROM Bug ORDER BY CODE
SELECT BugCode, IsValid FROM @BugRep ORDER BY BugCode

UPDATE @BugRep                          -- Can't be [@BugRep] ("Invalid object name '@BugRep'.")
SET IsValid = 'N'
WHERE NOT EXISTS (
    SELECT *
    FROM BUG b
    WHERE [@BugRep].BUGCODE = b.CODE    -- Can't be @BugRep ("Must declare the scalar variable "@BugRep".")
)

SELECT BugCode, IsValid FROM @BugRep ORDER BY BugCode

UPDATE @BugRep                          -- Can be either @BugRep or [@BugRep]
SET IsValid = 'Y'
FROM @BugRep                            -- Can't be [@BugRep] ("Invalid object name '@BugRep'.")
LEFT OUTER JOIN BUG
ON [@BugRep].BUGCODE = BUG.CODE         -- Can't be @BugRep ("Must declare the scalar variable "@BugRep".")
WHERE BUG.CODE IS NOT NULL

SELECT BugCode, IsValid FROM @BugRep ORDER BY BugCode

DROP TABLE Bug
GO

回答3:

Here's a version of the previous two using aliases to get around your issue:

UPDATE @BugRep
SET IsValid = 'N'
FROM @BugRep BR
    LEFT JOIN BUG B
        ON BR.BUGCode = B.CODE
WHERE B.CODE is null

This also avoids the inefficiencies related to "is not null" and "not exists".