如何使用邏輯條件在現有表上創建查詢並使用bool數據構建表（視圖）？

Question

我所擁有的是MS-SQL數據庫，用於存儲來自安裝在某些車輛（每車1-3輛設備）的設備的數據/信息。

目前，數據庫中有一張名爲Communication的表 - 用於存儲設備連接到TCP服務器時每個信息的大表。記錄一個接一個地添加（僅在這裏插入）。

表看起來是這樣的：

我需要的是一個SQL查詢（指令/語句）爲所謂的「每週通訊狀態」創建表（視圖），其中我可以看到是否/如何在汽車在過去的7天已通知...像下表：

Answer 1

作爲替代上面，給，你知道會有在輸出中只有7個日期列可以執行手動操作，而不是使用PIVOT操作符。

See SQLFiddle

select VehicleNumber, 
     CASE WHEN SUM(CASE WHEN DATEDIFF(d,DateTimeCommunication, DATEADD(d,-7,GETDATE())) = 0 THEN 1 ELSE 0 END) > 0 THEN 'YES' Else 'NO' END AS [7 Days Ago] 
     ,CASE WHEN SUM(CASE WHEN DATEDIFF(d,DateTimeCommunication, DATEADD(d,-6,GETDATE())) = 0 THEN 1 ELSE 0 END) > 0 THEN 'YES' Else 'NO' END AS [6 Days Ago] 
     ,CASE WHEN SUM(CASE WHEN DATEDIFF(d,DateTimeCommunication, DATEADD(d,-5,GETDATE())) = 0 THEN 1 ELSE 0 END) > 0 THEN 'YES' Else 'NO' END AS [5 Days Ago] 
     ,CASE WHEN SUM(CASE WHEN DATEDIFF(d,DateTimeCommunication, DATEADD(d,-4,GETDATE())) = 0 THEN 1 ELSE 0 END) > 0 THEN 'YES' Else 'NO' END AS [4 Days Ago] 
     ,CASE WHEN SUM(CASE WHEN DATEDIFF(d,DateTimeCommunication, DATEADD(d,-3,GETDATE())) = 0 THEN 1 ELSE 0 END) > 0 THEN 'YES' Else 'NO' END AS [3 Days Ago] 
     ,CASE WHEN SUM(CASE WHEN DATEDIFF(d,DateTimeCommunication, DATEADD(d,-2,GETDATE())) = 0 THEN 1 ELSE 0 END) > 0 THEN 'YES' Else 'NO' END AS [2 Days Ago] 
     ,CASE WHEN SUM(CASE WHEN DATEDIFF(d,DateTimeCommunication, DATEADD(d,-1,GETDATE())) = 0 THEN 1 ELSE 0 END) > 0 THEN 'YES' Else 'NO' END AS [1 Days Ago] 
     ,CASE WHEN SUM(CASE WHEN DATEDIFF(d,DateTimeCommunication, GETDATE()) = 0 THEN 1 ELSE 0 END) > 0 THEN 'YES' Else 'NO' END AS [0 Days Ago] 
from Communications 
GROUP BY VehicleNumber 

Answer 2

這裏是一個動態的PIVOT的方法。

CREATE TABLE #temp(equipmentID int, vehicleNumber int, DateTimeCommunication datetime) 

INSERT INTO #temp(equipmentID, vehicleNumber, DateTimeCommunication) 
VALUES (1,100,GETDATE()), 
     (2,110,GETDATE()), 
     (3,120,GETDATE()), 
     (5,140,GETDATE()), 
     (1,100,DATEADD(day,-8,GETDATE())), 
     (3,120,DATEADD(day,-8,GETDATE())), 
     (4,130,DATEADD(day,-8,GETDATE())), 
     (5,140,DATEADD(day,-8,GETDATE())) 

DECLARE @sql nvarchar(max), @columns nvarchar(max), @columnsSelect nvarchar(max) 

SELECT @columns = COALESCE(@columns + N',['+CONVERT(nvarchar(max),dateCom)+N']',N'['+CONVERT(nvarchar(max),dateCom)+N']') 
FROM (
    SELECT DISTINCT CONVERT(date, DateTimeCommunication) as dateCom 
    FROM #temp 
) as allDates 
ORDER BY dateCom 

SELECT @columnsSelect = COALESCE(@columnsSelect + N',ISNULL(['+CONVERT(nvarchar(max),dateCom)+N'],N''NO'') as '''+CONVERT(nvarchar(max),dateCom)+'''', 
            N'ISNULL(['+CONVERT(nvarchar(max),dateCom)+N'],N''NO'') as '''+CONVERT(nvarchar(max),dateCom)+'''') 
FROM (
    SELECT DISTINCT CONVERT(date, DateTimeCommunication) as dateCom 
    FROM #temp 
) as allDates 
ORDER BY dateCom 

SET @sql = N'SELECT pvt.vehicleNumber, '+@columnsSelect+' 
FROM (
    SELECT t.equipmentID, t.vehicleNumber, CONVERT(date,DateTimeCommunication) as dateCom, 
     CASE WHEN t.DateTimeCommunication BETWEEN DATEADD(day,-7,GETDATE()) AND GETDATE() 
      THEN N''YES'' 
      ELSE N''NO'' 
     END as communicated 
    FROM #temp t 
) as dat 
PIVOT(
    MAX(communicated) 
    FOR dateCom IN('+@columns+') 
) as pvt' 
PRINT(@sql) 
EXEC (@sql) 

DROP TABLE #temp 

如果你不需要它的動態或只爲指定日期範圍內，只需再次簡化了它這樣的：

CREATE TABLE #temp(equipmentID int, vehicleNumber int, DateTimeCommunication datetime) 

INSERT INTO #temp(equipmentID, vehicleNumber, DateTimeCommunication) 
VALUES (1,100,GETDATE()), 
     (2,110,GETDATE()), 
     (3,120,GETDATE()), 
     (5,140,GETDATE()), 
     (1,100,DATEADD(day,-8,GETDATE())), 
     (3,120,DATEADD(day,-8,GETDATE())), 
     (4,130,DATEADD(day,-8,GETDATE())), 
     (5,140,DATEADD(day,-8,GETDATE())) 

SELECT * 
FROM (
    SELECT t.equipmentID, t.vehicleNumber, CONVERT(date,DateTimeCommunication) as dateCom, 
     CASE WHEN t.DateTimeCommunication BETWEEN DATEADD(day,-7,GETDATE()) AND GETDATE() 
      THEN N'YES' 
      ELSE N'NO' 
     END as communicated 
    FROM #temp t 
) as dat 
PIVOT(
    MAX(communicated) 
    FOR dateCom IN([2015-06-23]) --needs to be changed on different date! 
) as pvt 

DROP TABLE #temp