Mysql SCD类型2合并逻辑导致目标表中出现重复项

我试图在大查询中实现SCD类型2合并逻辑

我是用3种设置方法完成这项工作的，但每次我运行合并逻辑脚本时，它似乎都会将记录推送到目标表中，即使没有新记录

步骤1：当记录与自然键匹配时，停用目标表中的活动记录 步骤2：在目标表中插入先前不存在的新记录 步骤3：将更新的记录从源表插入目标表我在这里得到了重复的记录 这是我的密码

CREATE
    OR REPLACE PROCEDURE `processed.sp_merge_example` (job_run_id INT64) OPTIONS (strict_mode = false)

BEGIN
    DECLARE run_id INT64 DEFAULT job_run_id;

    ---checking for natural keys for updates
    MERGE INTO `processed.<Destination table>` AS T
    USING `transient.<Source table>` AS S
        ON T.<Destination table>_fingerprint = S.<Source table>_fingerprint
    WHEN MATCHED
        AND S.type2_checksum != T.type2_checksum
        AND T.current_flg = 'Y'
        THEN
            UPDATE
            ---updating the records in the final table which has updates in the incremental load.
            SET T.modified_datetime = current_datetime(),
                T.modified_by = CAST(run_id AS STRING),
                T.end_datetime = current_datetime(),
                T.current_flg = 'N'
    WHEN NOT MATCHED
        THEN
            ---inserting new records.
            INSERT (
                <Source table columns>
                source_type,
                material_sales_fingerprint,
                type2_checksum,
                start_datetime,
                end_datetime,
                current_flg,
                created_by,
                created_datetime,
                modified_by,
                modified_datetime
                )
            VALUES (
                <Source table values>
                S.source_type,
                S.material_sales_fingerprint,
                S.type2_checksum,
                current_datetime(),
                parse_date('%Y%m%d', '99991231'),
                'Y',
                CAST(run_id AS STRING),
                current_datetime(),
                CAST(run_id AS STRING),
                current_datetime()
                );

    -- insert into newly updated records
    INSERT `processed.dim_material_sales` (
        <Source table columns>
        source_type,
        material_sales_fingerprint,
        type2_checksum,
        start_datetime,
        end_datetime,
        current_flg,
        created_by,
        created_datetime,
        modified_by,
        modified_datetime
        )
    SELECT 
        <Source table columns>
        ST.source_type,
        ST.material_sales_fingerprint,
        ST.type2_checksum,
        current_datetime(),
        parse_date('%Y%m%d', '99991231'),
        'Y',
        CAST(run_id AS STRING),
        current_datetime(),
        CAST(run_id AS STRING),
        current_datetime()
    FROM (
        SELECT x.*
        FROM `transient.<Source table>` x
        JOIN `processed.<Destination table>` y 
        ON x.<Source table>_fingerprint = y.<Source table>_fingerprint
        WHERE x.type2_checksum != y.type2_checksum and y.current_flg = 'N' 
        ) ST
END; 

-最后的这段逻辑导致了重复

---

如果我用源代码中的相同记录运行合并逻辑n次，那么目标表应该有相同的记录，但使用上述逻辑，每次运行合并逻辑时，源代码中更新的记录总是被插入目标表。我已经测试了很多次，不确定哪里出了问题。有人能帮我理解吗。

用以下逻辑解决了这个问题

CREATE OR REPLACE PROCEDURE `<stored_proc_name >`(job_run_id INT64) OPTIONS(strict_mode=false)
BEGIN
DECLARE run_id INT64 DEFAULT job_run_id;

-- Inserting updated records coming as part of incremental load to Destination first.
INSERT
  `<destination_table>`(
    <Target_table_columns>,
    tablename_fingerprint,
    type2_checksum,
    start_datetime,
    end_datetime,
    current_flg,
    created_by,
    created_datetime,
    modified_by,
    modified_datetime)

SELECT
   ST.<Target_table_columns>
  current_datetime(),
  cast(parse_timestamp('%Y%m%d%H%M%S', '99991231235959') as datetime),
  'Y',
  CAST(run_id AS STRING),
  current_datetime(),
  CAST(run_id AS STRING),
  current_datetime()
FROM (
  SELECT x.*
  FROM
    `<source_table>` x
  JOIN
    `<destination_table>` y
  ON
    y.<destination_table_fingerprint_column> = x.<source_temp_table_fingerprint_column>
    Where x.type2_checksum != y.type2_checksum and y.current_flg = 'Y') ST;
    
---Merge Process Starts
    
MERGE INTO
  `<destination_table>` AS T
USING
  `<source_table>` AS S
ON
  T.<destination_table_fingerprint_column> = S.<source_temp_table_fingerprint_column>

  -- Updating older version of the records.
  WHEN MATCHED
        AND S.type2_checksum != T.type2_checksum
        AND T.current_flg = 'Y'
        THEN
            UPDATE
            SET T.modified_datetime = current_datetime(),
                T.modified_by = CAST(run_id AS STRING),
                T.end_datetime = current_datetime(),
                T.current_flg = 'N'

    -- Inserting new records from temp to final table
  WHEN NOT MATCHED
  THEN
INSERT
  (
    <Target_table_columns>,
    tablename_fingerprint,
    type2_checksum,
    start_datetime,
    end_datetime,
    current_flg,
    created_by,
    created_datetime,
    modified_by,
    modified_datetime
    )
VALUES
  (
    <S.Target_table_columns>,
    current_datetime(),
    cast(parse_timestamp('%Y%m%d%H%M%S', '99991231235959') as datetime),
    'Y',
    CAST(run_id AS STRING),
    current_datetime(),
    CAST(run_id AS STRING),
    current_datetime()
        );
END;

CREATE OR REPLACE PROCEDURE `<stored_proc_name >`(job_run_id INT64) OPTIONS(strict_mode=false)
BEGIN
DECLARE run_id INT64 DEFAULT job_run_id;

-- Inserting updated records coming as part of incremental load to Destination first.
INSERT
  `<destination_table>`(
    <Target_table_columns>,
    tablename_fingerprint,
    type2_checksum,
    start_datetime,
    end_datetime,
    current_flg,
    created_by,
    created_datetime,
    modified_by,
    modified_datetime)

SELECT
   ST.<Target_table_columns>
  current_datetime(),
  cast(parse_timestamp('%Y%m%d%H%M%S', '99991231235959') as datetime),
  'Y',
  CAST(run_id AS STRING),
  current_datetime(),
  CAST(run_id AS STRING),
  current_datetime()
FROM (
  SELECT x.*
  FROM
    `<source_table>` x
  JOIN
    `<destination_table>` y
  ON
    y.<destination_table_fingerprint_column> = x.<source_temp_table_fingerprint_column>
    Where x.type2_checksum != y.type2_checksum and y.current_flg = 'Y') ST;
    
---Merge Process Starts
    
MERGE INTO
  `<destination_table>` AS T
USING
  `<source_table>` AS S
ON
  T.<destination_table_fingerprint_column> = S.<source_temp_table_fingerprint_column>

  -- Updating older version of the records.
  WHEN MATCHED
        AND S.type2_checksum != T.type2_checksum
        AND T.current_flg = 'Y'
        THEN
            UPDATE
            SET T.modified_datetime = current_datetime(),
                T.modified_by = CAST(run_id AS STRING),
                T.end_datetime = current_datetime(),
                T.current_flg = 'N'

    -- Inserting new records from temp to final table
  WHEN NOT MATCHED
  THEN
INSERT
  (
    <Target_table_columns>,
    tablename_fingerprint,
    type2_checksum,
    start_datetime,
    end_datetime,
    current_flg,
    created_by,
    created_datetime,
    modified_by,
    modified_datetime
    )
VALUES
  (
    <S.Target_table_columns>,
    current_datetime(),
    cast(parse_timestamp('%Y%m%d%H%M%S', '99991231235959') as datetime),
    'Y',
    CAST(run_id AS STRING),
    current_datetime(),
    CAST(run_id AS STRING),
    current_datetime()
        );
END;