取區分記錄與JOIN

Question

我想採取不同的病人記錄，並顯示在一個網格

耐心表

PatientId, FirstName, LastName, City 

的預訂表

BookingId, PatientId, CategoryId, BookingDate 

下方運行查詢給出重複的患者記錄。發生這種情況是因爲我爲不同日期的同一患者預訂了3次。該查詢使得加入並帶來3個患者記錄而不是1個患者記錄。

SELECT DISTINCT PAT.PatientId 
,PAT.FirstName 
,PAT.LastName  

,ROW_NUMBER() OVER (ORDER BY PAT.PatientId DESC) AS RowNumber 
INTO #itemSearch 
FROM dbo.Patient AS PAT 

INNER JOIN dbo.Booking AS B 
ON PAT.PatientId = B.PatientId WHERE B.CategoryId = 1 

如果我刪除這一行，我只得到1.但我需要這個臨時表的其他尋呼過程。

ROW_NUMBER() OVER (ORDER BY PAT.PatientId DESC) AS RowNumber INTO #itemSearch 

即使他們有3個預訂，我怎樣才能得到1個病人？

Answer 1

使用GROUP BY子句

SELECT PAT.PatientId 
     ,PAT.FirstName 
     ,PAT.LastName  
     ,ROW_NUMBER() OVER (ORDER BY PAT.PatientId DESC) AS RowNumber 
INTO #itemSearch 
FROM dbo.Patient AS PAT 
    INNER JOIN dbo.Booking AS B 
    ON PAT.PatientId = B.PatientId 
WHERE B.CategoryId = 1 
GROUP BY PAT.PatientId, PAT.FirstName, PAT.LastName 

或使用DISTINCT與DENSE_RANK()排名功能

SELECT DISTINCT PAT.PatientId 
     ,PAT.FirstName 
     ,PAT.LastName  
     ,DENSE_RANK() OVER (ORDER BY PAT.PatientId DESC) AS RowNumber 
INTO #itemSearch 
FROM dbo.Patient AS PAT 
    INNER JOIN dbo.Booking AS B 
    ON PAT.PatientId = B.PatientId 
WHERE B.CategoryId = 1