Question

我正在尝试为此DELETE（和SELECT）查询获得最快的性能。是否有更好的方法来删除记录，因为这需要超过10分钟才能运行？我想它必须做它自己的排序和合并，直到它能找到记录。

SELECT COUNT([VISIT_ID])
FROM [dbo].[I2B2_SRC_VISITS]
WHERE [PATIENT_ID] NOT IN (
    SELECT [PATIENT_ID] FROM [dbo].[I2B2_SRC_PATIENT]
)

DELETE FROM [dbo].[I2B2_SRC_VISITS]
WHERE [PATIENT_ID] NOT IN (
    SELECT [PATIENT_ID] FROM [dbo].[I2B2_SRC_PATIENT]
)

编辑：我无法将DELETE放在该查询的前面，就像我使用SELECT一样。但这是DELETE语句的最终结果。

DELETE FROM [dbo].[I2B2_SRC_VISITS]
WHERE [VISIT_ID] IN
(
    SELECT a.[VISIT_ID]
    FROM    [dbo].[I2B2_SRC_VISITS] a
            LEFT JOIN [dbo].[I2B2_SRC_PATIENT] b
                ON a.[PATIENT_ID] = b.[PATIENT_ID]
    WHERE b.[PATIENT_ID]  IS NULL
)

Answer 1

如何通过JOIN来完成？

DELETE  a
FROM    [dbo].[I2B2_SRC_VISITS] a
        LEFT JOIN [dbo].[I2B2_SRC_PATIENT] b
            ON a.[PATIENT_ID] = b.[PATIENT_ID]
WHERE   b.[PATIENT_ID] IS NULL

确保两个表中的列[PATIENT_ID]都具有键定义，这使得它更快。

右。 NOT EXIST比较好。

DELETE  a 
FROM    [dbo].[I2B2_SRC_VISITS] a 
WHERE   NOT EXISTS
        ( 
            SELECT  1 
            FROM    [dbo].[I2B2_SRC_PATIENT] b
            WHERE   a.[PATIENT_ID] = b.[PATIENT_ID] 
        )

使用DELETE逻辑NOT IN嵌套查询的最快性能

1 个答案: