Question

这是表格-CANo有数百个客户帐户，每个客户帐户都有成千上万的记录。

我想找到每个客户的最新最新记录。

现在，我首先运行以下查询以获取所有唯一的CANo。在桌子上

SELECT DISTINCT [CANo] 
  FROM [energymeters].[datalogging].[ardeecity]
  ORDER BY CANo

然后另一个查询以获取最大的时间戳，以查找此特定CANo的最后一条记录或最新记录。

但是我的实际要求是运行查询以完成这两项任务并给我一张桌子。

USE [energymeters]
GO

SELECT
      MAX(TimeStamp) AS TIMESTAMP

  FROM [datalogging].[ardeecity]

  WHERE CANo = 1220110001

GO

表设计类似于以下代码---

USE [energymeters]
GO

CREATE TABLE [datalogging].[ardeecity](
    [IndexRecords] [int] IDENTITY(1,1) NOT NULL,
    [TimeStamp] [datetime] NOT NULL,
    [CANo] [bigint] NULL,
    [DCUID] [int] NOT NULL,
    [DevID] [tinyint] NOT NULL,
    [EnergyEB] [decimal](15, 2) NULL,
    [EnergyDG] [decimal](15, 2) NULL,
    [EnergyBalance] [decimal](15, 2) NULL,
    [TimeAvailable] [int] NULL,
    [LastTopUpUnits] [decimal](15, 2) NULL,
    [LastTopUpDateTime] [datetime] NULL,
    [PreviousDayEnergy] [decimal](10, 2) NULL,
    [PresentDayEnergy] [decimal](10, 2) NULL,
    [PreviousMonthEnergyEB] [decimal](10, 2) NULL,
    [PreviousMonthEnergyDG] [decimal](10, 2) NULL,
    [PresentMonthEnergyEB] [decimal](10, 2) NULL,
    [PresentMonthEnergyDG] [decimal](10, 2) NULL,
    [RelayStatus] [tinyint] NULL,
    [EBDGStatus] [tinyint] NULL,
    [VoltageR] [decimal](8, 2) NULL,
    [VoltageY] [decimal](8, 2) NULL,
    [VoltageB] [decimal](8, 2) NULL,
    [CurrentR] [decimal](8, 2) NULL,
    [CurrentY] [decimal](8, 2) NULL,
    [CurrentB] [decimal](8, 2) NULL,
    [PFTotal] [decimal](5, 3) NULL,
    [Frequency] [decimal](5, 2) NULL,
    [KVATotal] [decimal](10, 2) NULL,
    [KWTotal] [decimal](10, 2) NULL,
    [KVARTotal] [decimal](10, 2) NULL,
    [TamperStatus] [tinyint] NULL,
    [LastMonthRupees] [decimal](15, 2) NULL,
    [TokenStatus] [tinyint] NULL,
    [PhaseType] [tinyint] NULL,
    [MaximumLoadEB] [decimal](10, 2) NULL,
    [MaximumLoadDG] [decimal](10, 2) NULL,
    [MaximumDemandEB] [decimal](10, 2) NULL,
    [MDIDateTimeEB] [datetime] NULL,
    [MaximumDemandDG] [decimal](10, 2) NULL,
    [MDIDateTimeDG] [datetime] NULL,
    [BalanceRupees] [decimal](15, 2) NULL,
    [MeterSerialNo] [nvarchar](50) NULL,
    [Dummy1] [nvarchar](50) NULL,
    [Dummy2] [nvarchar](50) NULL,
    [Dummy3] [nvarchar](50) NULL,
    [Token] [nvarchar](50) NULL,
    [TokenRTC] [nvarchar](50) NULL,
    [EBTariff] [decimal](10, 2) NULL,
    [DGTariff] [decimal](10, 2) NULL,
    [AdminStatus] [tinyint] NULL,
    [SuperAdminStatus] [tinyint] NULL,
    [PaymentType] [tinyint] NULL,
    [IntegrationType] [tinyint] NULL,
    [EmergencyPushButton] [tinyint] NULL,
    [MDIDelayTime] [tinyint] NULL,
    [SerialNoWriatable] [tinyint] NULL,
    [VoltageMultFactorR] [decimal](10, 2) NULL,
    [VoltageMultFactorY] [decimal](10, 2) NULL,
    [VoltageMultFactorB] [decimal](10, 2) NULL,
    [CurrentMultFactorR] [decimal](10, 2) NULL,
    [CurrentMultFactorY] [decimal](10, 2) NULL,
    [CurrentMultFactorB] [decimal](10, 2) NULL,
    [PhaseErrorR] [decimal](10, 2) NULL,
    [PhaseErrorY] [decimal](10, 2) NULL,
    [PhaseErrorB] [decimal](10, 2) NULL,
    [DeviceID] [int] NULL,
    [Password] [int] NULL,
    [RAMClear] [tinyint] NULL,
    [EBDGStatusWritable] [tinyint] NULL,
    [MDIResetWritable] [tinyint] NULL,
    [VoltageRReadOnly] [decimal](10, 2) NULL,
    [VoltageYReadOnly] [decimal](10, 2) NULL,
    [VoltageBReadOnly] [decimal](10, 2) NULL,
    [CurrentRReadOnly] [decimal](10, 2) NULL,
    [CurrentYReadOnly] [decimal](10, 2) NULL,
    [CurrentBReadOnly] [decimal](10, 2) NULL,
    [KWRReadOnly] [decimal](10, 2) NULL,
    [KWYReadOnly] [decimal](10, 2) NULL,
    [KWBReadOnly] [decimal](10, 2) NULL,
    [MeterStatus] [nvarchar](50) NULL,
    [GPRSStatus] [nvarchar](50) NULL,
    [TagNo] [int] NOT NULL
) ON [PRIMARY]
GO

每个CANo或客户帐户都具有成千上万个具有相同CANo的数据记录条目，并且成千上万的客户具有独特的CANo。

如何在每个CANo中查找最新或最后一条记录

非常感谢您的帮助-

查找编号最大的字段的最后一条记录。的条目

0 个答案: