Процедура Sql не работает должным образом

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Привет,

Я использую нижеприведенную процедуру для вставки данных в таблицу, если запись не существует другого обновления, но вставка работает нормально, и обновление над правильными записями, я не знаю, где я делаю неправильно.

Что я уже пробовал:

USE [AnsiSchoolDB2]
GO
/****** Object:  StoredProcedure [dbo].[GenFeePayment]    Script Date: 3/9/2019 11:22:13 AM ******/
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
-- =============================================
-- Author:		<Author,,Name>
-- Create date: <Create Date,,>
-- Description:	<Description,,>
-- =============================================
ALTER PROC [dbo].[GenFeePayment]
@cid int,
@pid int
	As
	BEGIN
	IF NOT EXISTS (SELECT * FROM tblFeePayment WHERE tblFeePayment.ClassID =@cid AND tblFeePayment.FeePartID =@pid)
  BEGIN
  INSERT INTO [dbo].[tblFeePayment]
           ([enrollID] ,[AdmissionNo] ,[classfee] ,ClassID ,[catdiscount],[studiscount] ,FeePartID ,[feeparticular]
) 

  SELECT  t.EnrollID,t.AdmissionNo, t.FeeAmount,t.ClassID,t.CatDiscountAmount,t.StuDiscountAmount,t.FeePartID,t.particular
  
  FROM

  (SELECT DiSTINCT tblEnrollment.EnrollID,tblStudent.AdmissionNo, tblStuCategory.CategoryID,tblStuCategory.Category,tblClass.ClassID,tblClass.ClassName,tblFeeParts.FeePartID,tblFeeParts.particular, tblClassFee.FeeAmount,
tblCatDiscount.Discount AS CatDiscount, tblCatDiscount.is_Percent AS CatPercent,
ISNULL((CASE WHEN tblCatDiscount.is_Percent = 1 THEN (tblClassFee.FeeAmount * tblCatDiscount.Discount) / 100 
ELSE tblCatDiscount.Discount END), 0) 
                         AS CatDiscountAmount,
tblStuDiscount.Discount AS StuDiscount, 

tblStuDiscount.is_percent AS StuPercent, 

ISNULL((CASE WHEN tblStuDiscount.is_percent = 1 THEN (tblClassFee.FeeAmount * tblStuDiscount.Discount) 
                         / 100 ELSE tblStuDiscount.Discount END), 0) AS StuDiscountAmount
  FROM [tblEnrollment]
  INNER JOIN tblClassFee ON tblClassFee.ClassID = tblEnrollment.ClassID
  INNER JOIN tblStudent ON tblStudent.StudentID = tblEnrollment.StudentID
  INNER JOIN tblStuCategory ON tblStuCategory.CategoryID = tblEnrollment.CategoryID
  INNER JOIN tblClass ON tblClass.ClassID = tblClassFee.ClassID
  INNER JOIN tblFeeParts ON tblFeeParts.FeePartID = tblClassFee.FeePartID
  INNER JOIN tblCatDiscount ON tblEnrollment.CategoryID = tblCatDiscount.CategoryID
  LEFT JOIN tblStuDiscount ON tblStuDiscount.EnrollID = tblEnrollment.EnrollID AND tblStuDiscount.FeeTypeID = tblFeeParts.FeeTypeID ) t
  WHERE ClassID =@cid AND FeePartID =@pid 
END
ELSE
BEGIN
  UPDATE [tblFeePayment]
        SET   [EnrollID]= p.EnrollID ,[AdmissionNo] =p.AdmissionNo,[classfee]=p.FeeAmount
		 ,ClassID=p.ClassID ,[catdiscount]=p.CatDiscountAmount,[studiscount]=p.StuDiscountAmount ,FeePartID=p.FeePartID ,
		 [feeparticular]=p.particular
  FROM

  (SELECT DiSTINCT tblEnrollment.EnrollID,tblStudent.AdmissionNo, tblStuCategory.CategoryID,tblStuCategory.Category,tblClass.ClassID,tblClass.ClassName,tblFeeParts.FeePartID,tblFeeParts.particular, tblClassFee.FeeAmount,
tblCatDiscount.Discount AS CatDiscount, tblCatDiscount.is_Percent AS CatPercent,ISNULL((CASE WHEN tblCatDiscount.is_Percent = 1 THEN (tblClassFee.FeeAmount * tblCatDiscount.Discount) / 100 ELSE tblCatDiscount.Discount END), 0) 
                         AS CatDiscountAmount,
tblStuDiscount.Discount AS StuDiscount, tblStuDiscount.is_percent AS StuPercent, ISNULL((CASE WHEN tblStuDiscount.is_percent = 1 THEN (tblClassFee.FeeAmount * tblStuDiscount.Discount) 
                         / 100 ELSE tblStuDiscount.Discount END), 0) AS StuDiscountAmount
  FROM [tblEnrollment]
  INNER JOIN tblClassFee ON tblClassFee.ClassID = tblEnrollment.ClassID
  INNER JOIN tblStudent ON tblStudent.StudentID = tblEnrollment.StudentID
  INNER JOIN tblStuCategory ON tblStuCategory.CategoryID = tblEnrollment.CategoryID
  INNER JOIN tblClass ON tblClass.ClassID = tblClassFee.ClassID
  INNER JOIN tblFeeParts ON tblFeeParts.FeePartID = tblClassFee.FeePartID
  INNER JOIN tblCatDiscount ON tblEnrollment.CategoryID = tblCatDiscount.CategoryID
  LEFT JOIN tblStuDiscount ON tblStuDiscount.EnrollID = tblEnrollment.EnrollID AND tblStuDiscount.FeeTypeID = tblFeeParts.FeeTypeID ) p
  WHERE p.ClassID =@cid AND p.FeePartID =@pid 
END
END

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