sql 2008 procedure

CREATE PROCEDURE csGorevDuzenle
 @duzenle int,
 @grup_ad varchar(30), 
 @islem_grubu varchar(30),
 @tamamlayan varchar(30),
 @kayit_zamani datetime,
 @sonuc_zamani varchar(30),
 @arayan varchar(30),
 @telefon varchar(20),
 @tanim varchar(1000),
 @durum varchar(15),
 @aciklama varchar(1000)
AS

  if @duzenle = 1 then
BEGIN
 UPDATE gorevler SET grup_ad = @islem_开发者_运维问答grubu, tamamlayan = @tamamlayan, sonuc_zamani = @sonuc_zamani, arayan = @arayan, telefon = @telefon, tanim = @tanim, durum = @durum, aciklama = @aciklama
 WHERE grup_ad = @grup_ad and kayit_zamani = @kayit_zamani 
END

  end if
GO

Msg 156, Level 15, State 1, Procedure csGorevDuzenle, Line 20 Incorrect syntax near the keyword 'then'. Msg 156, Level 15, State 1, Procedure csGorevDuzenle, Line 26 Incorrect syntax near the keyword 'if'.

This is not correct SQL syntax for an IF statement:

if @duzenle = 1 then

change to:

IF ( @duzenle = 1 )

T-SQL doesn't require you to write THEN after the IF statement. Change it to the following and it will work:

if @duzenle = 1 
BEGIN