MSSQL: ALTER TABLE in PROCEDURE

[temat]

Hi i got a problem when i try to Alter Table in the procedure. I have red that i need to place keyword IMMIDIATE but it dont work in mssql.

I need thede procedure to drop FOREIGN KEY, TRUNCATE and add FOREIGN KEY
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-- PUBLISHERS
ALTER PROCEDURE clearPublishers
AS
BEGIN TRANSACTION
ALTER TABLE dbo.Books
DROP CONSTRAINT FK_Publishers_Books

TRUNCATE TABLE dbo.Publishers

ALTER TABLE dbo.Books
ADD CONSTRAINT FK_Publishers_Books
FOREIGN KEY (pId)
REFERENCES dbo.Publishers (pId)
ON UPDATE CASCADE
COMMIT TRANSACTION
GO
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I got an Error :
[PHP]
Server: Msg 547, Level 16, State 1, Line 1
ALTER TABLE statement conflicted with COLUMN FOREIGN KEY constraint 'FK_Publishers_Books'. The conflict occurred in database '20.4.2007', table 'Publishers', column 'pId'.
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PLEASE HELP.