替换SQL服务器子查询，使查询更快，而不是抓取

我想加快这个查询，我试着各种连接，但我似乎无法结束与storm2 = 1和storm2 = 2重复查询一个加入替换SQL服务器子查询，使查询更快，而不是抓取

SELECT v1.id 
    ,v1.StormOut 
    ,v1.StormNo 
    ,v1.StormYes 
    ,v1.Equipment 
    ,(
     SELECT TimeOn 
     FROM [v_StormLog] 
     WHERE vehicle = v1.Vehicle 
      AND Storm2 = 1 
      AND CurrentDate = v1.CurrentDate 
     ) AS TimeOn 
    ,v1.Vehicle 
    ,v1.NAME 
    ,v1.Equipment AS Equip 
    ,(
     SELECT ScheduleOrig 
     FROM [v_StormLog] 
     WHERE vehicle = v1.Vehicle 
      AND Storm2 = 1 
      AND CurrentDate = v1.CurrentDate 
     ) AS ScheduleOrig 
    ,(
     SELECT ScheduleHTML 
     FROM [v_StormLog] 
     WHERE vehicle = v1.Vehicle 
      AND Storm2 = 1 
      AND CurrentDate = v1.CurrentDate 
     ) AS ScheduleHTML 
    ,(
     SELECT Schedule 
     FROM [v_StormLog] 
     WHERE vehicle = v1.Vehicle 
      AND Storm2 = 1 
      AND CurrentDate = v1.CurrentDate 
     ) AS Schedule 
    ,(
     SELECT TimeOff 
     FROM [v_StormLog] 
     WHERE vehicle = v1.Vehicle 
      AND Storm2 = 1 
      AND CurrentDate = v1.CurrentDate 
     ) AS TimeOff 
    ,v1.StormTimeOn 
    ,v1.StormTimeOff 
    ,v1.StormOut AS 'Out' 
    ,v1.StormYes AS Yes 
    ,v1.StormNo AS No 
    ,(
     SELECT comments 
     FROM [v_StormLog] 
     WHERE vehicle = v1.Vehicle 
      AND Storm2 = 1 
      AND CurrentDate = v1.CurrentDate 
     ) AS comments 
    ,v1.StormComments 
    ,(
     SELECT Comments 
     FROM [v_StormLog] 
     WHERE vehicle = v1.Vehicle 
      AND Storm2 = 1 
      AND CurrentDate = v1.CurrentDate 
     ) AS CommentsHTML 
    ,v1.Storm2 
FROM [v_StormLog] v1 
WHERE DATEADD(dd, DATEDIFF(dd, 0, v1.[CurrentDate]), 0) = @Date 
    AND v1.sgroup = 'North' 
    AND v1.Storm2 = @storm2 
ORDER BY v1.ScheduleHTML 
    ,v1.NAME

来源

2015-11-04 Brian Thornton

至少向我们展示执行计划http://stackoverflow.com/questions/7359702/how-do-i-obtain-a-query-execution-plan –

如果我记得没错，子查询的这种风格被转换到一个OUTER JOIN，但你应该检查你的执行计划以确保。假如是这样的话：

SELECT v1.id 
    ,v1.StormOut 
    ,v1.StormNo 
    ,v1.StormYes 
    ,v1.Equipment 
    ,v2.TimeOn AS TimeOn 
    ,v1.Vehicle 
    ,v1.NAME 
    ,v1.Equipment AS Equip 
    ,v2.ScheduleOrig AS ScheduleOrig 
    ,v2.ScheduleHTML AS ScheduleHTML 
    ,v2.Schedule AS Schedule 
    ,v2.TimeOff AS TimeOff 
    ,v1.StormTimeOn 
    ,v1.StormTimeOff 
    ,v1.StormOut AS 'Out' 
    ,v1.StormYes AS Yes 
    ,v1.StormNo AS No 
    ,v2.comments AS comments 
    ,v1.StormComments 
    ,v2.Comments AS CommentsHTML 
    ,v1.Storm2 
FROM [v_StormLog] v1 
LEFT JOIN [v_StormLog] v2 
    ON v2.vehicle = v1.Vehicle 
    AND v2.CurrentDate = v1.CurrentDate 
    AND v2.Storm2 = 1 
WHERE v1.[CurrentDate] >= @Date 
    AND v1.[CurrentDate] < DATEADD(dd,@Date,1) 
    AND v1.sgroup = 'North' 
    AND v1.Storm2 = @storm2 
ORDER BY v1.ScheduleHTML 
    ,v1.NAME

此外，这是不好的：DATEADD(dd, DATEDIFF(dd, 0, v1.[CurrentDate]), 0) = @Date。您正在告诉数据库加载每个日期时间值并在其上执行此功能，然后将其与固定值进行比较。你想避免这种情况。你想要针对静态值运行你的函数。在这里，@Date显然是以00:00作为时间分量的日期时间值。所以，在这种情况下，你可以做这样的：

v1.[CurrentDate] >= @Date 
AND v1.[CurrentDate] < DATEADD(dd,@Date,1)

这意味着“的currentdate是或@date后@date后一天的午夜之前”。

来源

2015-11-04 21:39:55

你需要自己加入表格。这会减少内部选择的数量。你还应该检查有适当的索引中查找的执行计划

SELECT v1.*, v2.*  -- update using the fields you need 
FROM [v_StormLog] v1 
JOIN [v_StormLog] v2 
    ON v2.vehicle = v1.Vehicle  
AND v2.CurrentDate = v1.CurrentDate 
WHERE 
    DATEADD(dd, DATEDIFF(dd, 0, v1.[CurrentDate]), 0) = @Date 
AND v1.sgroup = 'North' 
AND v1.Storm2 = @storm2  
AND v2.Storm2 = 1

你也已经重复场

,v1.StormOut 
,v1.StormNo 
,v1.StormYes

而且

,v1.StormOut AS 'Out' 
,v1.StormYes AS Yes 
,v1.StormNo AS No

来源

2015-11-04 21:28:40

替换SQL服务器子查询，使查询更快，而不是抓取

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