在 MERGE SQL 查询中遇到问题

Question

I have a requirement, insert/update data from staging table stgTbl to another table T2. If exists update, no matter how many duplicates are there. Similarly, if not exists insert directly T2. Very Simple. Since the staging table stgTb1 is scheduled job everyday. Sometime I would get multiple duplicate rows as well. So because of duplicates, merge statement producing an error:

"The MERGE statement attempted to UPDATE or DELETE the same row more than once. This happens when a target row matches more than one source row".

I tried with checksum but still getting because i may done wrongly in checksum. There is no primary key in both the tables (i removed, because otherwise i am getting primary key constraint error). Based on columns (account and ref_key2) should go with insert/update. I have tried with if else with exists also but somehow this is also not working if in case there are 0 records in the target table T2. SQL masters could solve this issue. Appreciate their knowledge share.

CREATE OR ALTER Trigger [dbo].[tr_Merge_Personal_Expense] on [dbo]. 
[Personal_Expense_Staging]
AFTER INSERT
AS

BEGIN

DECLARE @SummaryOfChanges TABLE(Change nvarchar(20));

         MERGE [dbo].[Personal_Expense] AS TARGET 
         USING (
         SELECT *,
                CHECKSUM(
                             ISNULL(CONVERT(nvarchar (3) ,[Client]),'0'),
                             ISNULL(CONVERT(nvarchar (50),[Text]),'0'),
                             ISNULL(CONVERT(nvarchar (10),[Cost_Center]),'0'),
                             ISNULL(CONVERT(nvarchar (2) ,[Posting_Period]),'0'),
                             ISNULL(CONVERT(nvarchar (10),[Profit]),'0') ,
                             ISNULL(CONVERT(nvarchar (2) ,[Document_Type]),'0'),
                             ISNULL(CONVERT(nvarchar (4) ,[Company_Code]),'0') ,
                             -- ISNULL(CONVERT(nvarchar (10),[Account]),'0'),
                             ISNULL(CONVERT(nvarchar (20),[Amount_In_Doc_Curr]),'0'),
                             ISNULL(CONVERT(nvarchar (5) ,[Document_Currency]),'0') ,
                             ISNULL(CONVERT(nvarchar (20),[Amount_In_local_Curr]),'0') ,
                             ISNULL(CONVERT(nvarchar (20),[Amount_In_Grp_Curr]),'0'),
                             ISNULL(CONVERT(nvarchar (25),[Group]),'0'),
                             [Posting_Date],
                             ISNULL(CONVERT(nvarchar (18), [Assignment]),'0'),
                             ISNULL(CONVERT(nvarchar (16), [Reference]),'0'),
                             ISNULL(CONVERT(nvarchar (20), [Reference_Key1]),'0') ,
                             --[Reference_Key2] [nvarchar](12) NOT NULL,
                             ISNULL(CONVERT(nvarchar (20), [Reference_Key3]),'0') ,
                             ISNULL(CONVERT(nvarchar (20), [Document_Number]),'0') ,
                             ISNULL(CONVERT(nvarchar (25), [Document_Header_Text]),'0') 
                 ) AS [HashChecksum]
         FROM
         [dbo].[Personal_Expense_Staging]
         ) AS SOURCE 
         ON (
                TARGET.[Reference_Key2] = SOURCE.[Reference_Key2] AND
                TARGET.[Account] = SOURCE.[Account] 
            )

         -----   Update 
         WHEN MATCHED AND ( TARGET.[HashChecksum] <> SOURCE.[HashChecksum] ) 
         THEN
         UPDATE SET  
                TARGET.[client] = SOURCE.[client],
                TARGET.[text] = SOURCE.[text],
                TARGET.[cost_center] = SOURCE.[cost_center],
                TARGET.[posting_period] = SOURCE.[posting_period],
                TARGET.[profit] = SOURCE.[profit],
                TARGET.[document_type]= SOURCE.[document_type],
                TARGET.[company_code] = SOURCE.[company_code],
                TARGET.[Account] = SOURCE.[Account],
                TARGET.[Amount_In_Doc_Curr] = SOURCE.[Amount_In_Doc_Curr],
                TARGET.[document_currency] = SOURCE.[document_currency],
                TARGET.[Amount_In_local_Curr] = SOURCE.[Amount_In_local_Curr],
                TARGET.[Amount_In_Grp_Curr] = SOURCE.[Amount_In_Grp_Curr],
                TARGET.[group] = SOURCE.[group],
                TARGET.[posting_date] = SOURCE.[posting_date],
                TARGET.[assignment] = SOURCE.[assignment],
                TARGET.[reference] = SOURCE.[reference],
                TARGET.[document_header_text] = SOURCE.[document_header_text],
                TARGET.[Last_updated_DateTime] = GETDATE(),
                TARGET.[HashChecksum] =  SOURCE.[HashChecksum]

         -- Insert 

         WHEN NOT MATCHED THEN
         INSERT ( 
                       [Client],
                       [text],
                       [cost_center],
                       [posting_period],
                       [profit],
                       [document_type],
                       [company_code],
                       [Account],
                       [Amount_In_Doc_Curr],
                       [document_currency],
                       [Amount_In_local_Curr],
                       [Amount_In_Grp_Curr],
                       [group],
                       [posting_date],
                       [assignment],
                       [reference],
                       [reference_key2],
                       [reference_key3],
                       [document_number],
                       [document_header_text],
                       [Last_updated_DateTime],
                       [HashChecksum]
         )
         VALUES (
                SOURCE.[client],
                SOURCE.[text],
                SOURCE.[cost_center],
                SOURCE.[posting_period],
                SOURCE.[profit],
                SOURCE.[document_type],
                SOURCE.[company_code],
                SOURCE.[Account],
                SOURCE.[Amount_In_Doc_Curr],
                SOURCE.[document_currency],
                SOURCE.[Amount_In_local_Curr],
                SOURCE.[Amount_In_Grp_Curr],
                SOURCE.[group],
                SOURCE.[posting_date],
                SOURCE.[assignment],
                SOURCE.[reference],
                SOURCE.[reference_key2],
                SOURCE.[reference_key3],
                SOURCE.[document_number],
                SOURCE.[document_header_text],
                GETDATE(),
                SOURCE.[HashChecksum]
         )

   OUTPUT $action INTO @SummaryOfChanges;

   DECLARE @RowsProcessed INT = 0;

   SELECT 
          @RowsProcessed = ISNULL([INSERT],0) + ISNULL([UPDATE],0) + ISNULL([DELETE],0)
   FROM (
         SELECT COUNT(*) ChangeCount, Change as ChangeType 
         FROM @SummaryOfChanges
         GROUP BY Change
   )Main
   PIVOT ( 
         MAX(ChangeCount)
         FOR ChangeType IN ([INSERT],[UPDATE],[DELETE])
   )Pvt;

   SELECT @RowsProcessed AS RowsProcessed;


CREATE OR ALTER TRIGGER [dbo].[tr_merge_personal_expense] 
ON personal_expense_staging 
AFTER INSERT AS

----- CASE 1: IF (ACCOUNT AND REF_KEY2) ARE MATCHED THEN UPDATE
IF EXISTS
(
  SELECT 
         *
  FROM   dbo.personal_expense p
         INNER JOIN inserted e
         ON p.[account] = e.[account] AND p.[reference_key2] = e.
         [reference_key2]
)
    BEGIN
        UPDATE target
          SET  
              target.[document_number] = source.[document_number],
              target.[client] = source.[client],
              target.[text] = source.[text],
              target.[cost_center] = source.[cost_center],
              target.[posting_period] = source.[posting_period],
              target.[profit] = source.[profit],
              target.[document_type] = source.[document_type],
              target.[company_code] = source.[company_code],
              target.[amount_in_doc_curr] = source.[amount_in_doc_curr],
              target.[document_currency] = source.[document_currency],
              target.[amount_in_local_curr] = source.[amount_in_local_curr],
              target.[amount_in_grp_curr] = source.[amount_in_grp_curr],
              target.[group] = source.[group],
              target.[posting_date] = source.[posting_date],
              target.[assignment] = source.[assignment],
              target.[reference] = source.[reference],
              target.[reference_key1] = source.[reference_key1],
              target.[reference_key3] = source.[reference_key3],
              target.[document_header_text] = source.[document_header_text],
              target.[last_updated_datetime] = GETDATE()
        FROM   personal_expense target
               INNER JOIN inserted source
               ON target.[account] = source.[account] 
               AND target.[reference_key2] = source.[reference_key2];
END;

        ------ CASE 2: IF (ACCOUNT AND REF_KEY2) ARE NOT MATCHED THEN INSERT
        IF NOT EXISTS
        (
          SELECT 
                 *
          FROM   dbo.personal_expense p
                 INNER JOIN inserted e
                 ON p.[account] = e.[account] AND p.[reference_key2] = e.
                 [reference_key2]
        )
            BEGIN
                INSERT INTO dbo.personal_expense
                (
                       [client],
                       [text],
                       [cost_center],
                       [posting_period],
                       [profit],
                       [document_type],
                       [company_code],
                       [account],
                       [amount_in_doc_curr],
                       [document_currency],
                       [amount_in_local_curr],
                       [amount_in_grp_curr],
                       [group],
                       [posting_date],
                       [assignment],
                       [reference],
                       [reference_key1],
                       [reference_key2],
                       [reference_key3],
                       [document_number],
                       [document_header_text],
                       [last_updated_datetime]
                )
                       SELECT 
                              source.[client],
                              source.[text],
                              source.[cost_center],
                              source.[posting_period],
                              source.[profit],
                              source.[document_type],
                              source.[company_code],
                              source.[account],
                              source.[amount_in_doc_curr],
                              source.[document_currency],
                              source.[amount_in_local_curr],
                              source.[amount_in_grp_curr],
                              source.[group],
                              source.[posting_date],
                              source.[assignment],
                              source.[reference],
                              source.[reference_key1],
                              source.[reference_key2],
                              source.[reference_key3],
                              source.[document_number],
                              source.[document_header_text],
                              GETDATE()
                       FROM   inserted source;
            END;

Answer 1

SO, you know that of duplicates, merge statement producing an error . Then simply remove the duplicates in your source clause, using DISTINCT :

SELECT DISTINCT *
FROM [dbo].[Personal_Expense_Staging]