SQL在选择中选择

Question

我正在创建一个将显示在SSRS报告中的数据集。

我在一项工作中查询，该工作在每个月的第一天以滚动方式将计数放入表[dbo].[CountMetersDue];该值在整个月中发生变化，因此需要在开始时进行快照。

我设置了使用自定义表达式生成累积趋势图的报告。基本上取一个值，再除以另一个百分比。因此，我有两个需要组合的查询......花了我很多时间让我的头脑圆满！

我只是需要最后一点的帮助。

SELECT (SELECT [Count] 
     FROM [MXPTransferDev].[dbo].[CountMetersDue] 
     WHERE [MXPTransferDev].[dbo].[CountMetersDue].[DateTime] = 
       [MXPTransferDev].[dbo].[Readings].[dateRead]) AS [MetersDue], 
     COUNT(readingid)          AS [TotalReadings], 
     CONVERT(DATE, dateread)        AS [dateRead] 
FROM [MXPTransferDev].[dbo].[Readings] 
WHERE ([MXPTransferDev].[dbo].[Readings].[dateRead] BETWEEN 
       '01-may-11' AND '31-may-11') 
     AND (webcontactid IS NOT NULL) 
     AND (meter = 1) 
GROUP BY CONVERT(DATE, [MXPTransferDev].[dbo].[Readings].[dateRead]) 

CREATE TABLE [dbo].[CountMetersDue](
    [Count] [int] NULL, 
    [DateTime] [datetime] NULL 
) ON [USER] 

GO 

ALTER TABLE [dbo].[CountMetersDue] 
ADD CONSTRAINT [DF_CountMetersDue_DateTime] DEFAULT (getdate()) FOR [DateTime] 
GO 

CREATE TABLE [dbo].[Readings](
    [readingId] [bigint] IDENTITY(1,1) NOT FOR REPLICATION NOT NULL, 
    [dateRead] [datetime] NOT NULL, 
    [meter] [int] NOT NULL, 
    [webcontactid] [bigint] NULL, 

Readings 

readingId meter reading dateRead   webcontactid 
583089 4 3662 2011-05-25 15:00:33.040   479 
583207 3 682  2011-05-25 15:00:33.027   479 
583088 2 98064 2011-05-25 15:00:33.007   479 

CountMetersDue 

Count DateTime 
2793 2011-12-01 00:00:00.000 
1057 2011-05-01 14:08:20.437 
610  2011-03-01 00:00:00.000 

Answer 1

在回答你问题的第二次刺（可能需要作出一些澄清自己之前的答案是正确的）：

/* DDL: 2 tables [CountMetersDue] & [Readings] 
    [CountMetersDue] 
     ([DateTime] datetime, 
     [Count] int) 

    [Readings] 
     ([ReadingId] bigint, 
     [dateRead] datetime, 
     [webcontactid] bigint, 
     [meter] int) 

    [CountMetersDue] - contains 1 record on the first of every month, with count of the number of readings at that date 
    [Readings] - contains all the individual readings 

    ie: 
     [CountMetersDue] 
     01-Jan-2011  1000 
     01-Feb-2011  2357 
     01-Mar-2011  3000 

     [Readings] 
     1 01-Jan-2011  11 1 
     2 02-Jan-2011  12 1 
     3 03-Jan-2011  13 1 
     ... 
*/ 

    SELECT 
    CONVERT(DATE, [dbo].[Readings].[dateRead]) AS dateRead, 
    COUNT([dbo].[Readings].[readingId]) AS TotalReadings, 
    [dbo].[CountMetersDue].[Count] AS MetersDue 

FROM 
    [CountMetersDue]    /* get all count meters due */ 
    left join [Readings]   /* get any corresponding Reading records 
             where the dateRead in the same month as 
             the CountMetersDue */ 
     on DATEPART(year, Readings.dateRead) = DATEPART(year, [CountMetersDue].[DateTime]) /* reading in same year as CountMetersDue */ 
     and DATEPART(month, Readings.dateRead) = DATEPART(month, [CountMetersDue].[DateTime]) /* reading in same month as CountMetersDue */ 
     WHERE ([MXPTransferDev].[dbo].[Readings].[dateRead]) BETWEEN 
       @StartDate AND @EndDate 
     AND (webcontactid IS NOT NULL) 
     AND (meter = 1) 
GROUP BY 
    [dbo].[CountMetersDue].[Count],CONVERT(DATE, [dbo].[Readings].[dateRead]) 

Answer 2

这将是您正在查找的查询吗？
可以通过将它们括在括号'（）'中来包含它们被调用的子查询。

SELECT (SELECT [Count] FROM [xxxxx].[dbo].[CountMetersDue] AS tabA WHERE tabA.[datefield] = tabB.dateRead) AS [MetersDue], COUNT(readingId) AS [TotalReadings], CONVERT(DATE, dateRead) AS [dateRead] 
FROM   [xxxxx] AS tabB 
WHERE  (dateRead BETWEEN @StartDate AND @EndDate) AND (webcontactid IS NOT NULL) AND (meter = 1) 
GROUP BY CONVERT(DATE, dateRead)