SQL查询与非存在优化

Question

我有以下查询，我直接在我的Code＆amp;把它放在数据表中。问题是执行此查询需要10多分钟。花费时间的主要部分是NON EXISTS。

SELECT 
    [t0].[PayrollEmployeeId], 
    [t0].[InOutDate], 
    [t0].[InOutFlag], 
    [t0].[InOutTime] 
FROM [dbo].[MachineLog] AS [t0] 
WHERE 
        ([t0].[CompanyId] = 1) 
    AND ([t0].[InOutDate] >= '2016-12-13')
    AND ([t0].[InOutDate] <= '2016-12-14') 
    AND 
    (   NOT (EXISTS(
        SELECT NULL AS [EMPTY] 
        FROM [dbo].[TO_Entry] AS [t1]  
        WHERE 
                ([t1].[EmployeeId] = [t0].[PayrollEmployeeId]) 
            AND ([t1]. [CompanyId] = 1) 
            AND ([t0].[PayrollEmployeeId] = [t1].[EmployeeId]) 
            AND (([t0].[InOutDate]) = [t1].[Entry_Date]) 
            AND ([t1].[Entry_Method] = 'M') 
        ))
    ) 
ORDER BY 
    [t0].[PayrollEmployeeId], [t0].[InOutDate]

有什么办法可以优化这个查询吗？为此做了什么工作。这花费了太多时间。

Answer 1

似乎您可以将NOT EXISTS转换为LEFT JOIN查询，第二个表返回NULL值

请检查以下SELECT并根据需要进行修改以满足您的要求

SELECT 
    [t0].[PayrollEmployeeId], [t0].[InOutDate], [t0].[InOutFlag], [t0].[InOutTime] 
FROM [dbo].[MachineLog] AS [t0] 
LEFT JOIN [dbo].[TO_Entry] AS [t1]
    ON  [t1].[EmployeeId] = [t0].[PayrollEmployeeId]
    AND [t0].[PayrollEmployeeId] = [t1].[EmployeeId]
    AND [t0].[InOutDate] = [t1].[Entry_Date]
    AND [t1]. [CompanyId] = 1
    AND [t1].[Entry_Method] = 'M'
WHERE 
        ([t0].[CompanyId] = 1) 
    AND ([t0].[InOutDate] >= '2016-12-13')
    AND ([t0].[InOutDate] <= '2016-12-14') 
    AND [t1].[EmployeeId] IS NULL
ORDER BY 
    [t0].[PayrollEmployeeId], [t0].[InOutDate]

Answer 2

您将意识到查询的执行计划中有一条信息性消息

通知缺少集群索引，执行时间为30％

似乎交易数据是基于某些日期字段（如进入时间）而发生的。 特别是在您的情况下，日期字段是聚簇索引的强大候选者。您可以在Entry_Date列上创建索引 我猜你已经在InOutDate上有一些索引了 您也可以尝试索引此字段