Question

早上好，

我得到了SQL查询的这一部分：

WITH HC AS (
    SELECT Dia, Mes, Anyo, Hora, Energia AS HidroConv 
    FROM Calendar 
    LEFT OUTER JOIN OMP_PDBC_STOTA O 
        ON Calendar.Y = O.Anyo AND Calendar.M = O.Mes 
        AND Calendar.D = O.Dia AND Calendar.H = O.Hora 
    WHERE (Codigo = 1) AND Calendar.dt BETWEEN '12/31/2013' AND '01/01/2014')

SELECT Calendar.dt AS Fecha, Calendar.Y, Calendar.M, Calendar.D, Calendar.H, 
       HC.HidroConv
FROM Calendar 
LEFT OUTER JOIN HC 
     ON Calendar.Y = HC.Anyo AND Calendar.M = HC.Mes 
     AND Calendar.D = HC.Dia AND Calendar.H = HC.Hora 
WHERE dt BETWEEN '12/31/2013' AND '01/01/2014' 
ORDER by dt, h

在WITH部分，我有另外12个查询。然后，在SELECT部分，我在WITH部分的每个SELECT上检索一列。在FROM部分，每个部分都有一个LEFT OUTER JOIN，总是在连接的左侧有Calendar。

这个大查询的执行时间超过2分钟，我迫切需要将时间缩短到15秒或更短。一些表，如OMP_PDBC_STOTA有300万行。

您对如何优化此查询有任何了解吗？

非常感谢你的帮助。

里卡多

Answer 1

此查询是否提供相同的输出？

SELECT Calendar.dt AS Fecha, Calendar.Y, Calendar.M, Calendar.D, Calendar.H, Energia AS HidroConv
FROM Calendar 
    LEFT OUTER JOIN OMP_PDBC_STOTA O 
        ON Calendar.Y = O.Anyo AND Calendar.M = O.Mes 
        AND Calendar.D = O.Dia AND Calendar.H = O.Hora 
WHERE  
    Calendar.dt BETWEEN '12/31/2013' AND '01/01/2014' 
    AND Codigo = 1
ORDER by dt, h

如果是这样，它会更快，告诉我，如果我错了，我会帮助你。

Answer 2

我发现我并不需要日历来获得相同的结果。

您如何看待这种做法？

SELECT  anyo, mes, dia, hora, Energia AS HidroConv
FROM OMP_PDBC_STOTA
WHERE  
    CAST(CAST(mes AS VARCHAR) + '/' + CAST(dia AS VARCHAR) + '/' + CAST(anyo AS VARCHAR) as datetime) BETWEEN '12/31/2013' AND '01/01/2014' 
    AND Codigo = 1
ORDER by mes,dia, hora

无法找到将smallints（mes，dia，anyo）转换为日期时间的正确方法。

优化SQL SERVER 2005查询

2 个答案: