內連接3表

Question

我有三個表，我試圖加入使用this問題中的示例。但是我得到的錯誤。

錯誤：

#1054 - Unknown column 'referrer.Referrer_Name' in 'field list' 

代碼：

SELECT pupils.Pupils_Surname, 
      pupils.Pupils_FirstName, 
      referrer.Referrer_Name, 
      progress_track.test_1, 
      progress_track.test_2, 
      progress_track.test_3, 
      progress_track.test_4, 
      progress_track.test_5, 
      progress_track.test_6, 
      progress_track.test_7, 
      progress_track.test_8, 
      progress_track.test_9, 
      progress_track.test_10 
    FROM pupils 
    INNER JOIN progress_track ON progress_track.Progress_Report_Pupils_ID=pupils.Pupils_ID; 
    INNER JOIN referrer ON pupils.Pupils_Referrer, referrer.Referrer_ID ; 

Answer 1

首先我要強調查詢中的故障：

1）查詢意外結束了一個排字錯誤

2）最後的INNER JOIN包含語法錯誤。

我已經強調了故障在圖像如下：

補救措施：

SELECT 
    pupils.Pupils_Surname, 
    pupils.Pupils_FirstName, 
    referrer.Referrer_Name, 
    progress_track.test_1, 
    progress_track.test_2, 
    progress_track.test_3, 
    progress_track.test_4, 
    progress_track.test_5, 
    progress_track.test_6, 
    progress_track.test_7, 
    progress_track.test_8, 
    progress_track.test_9, 
    progress_track.test_10 
FROM 
    pupils 
INNER JOIN progress_track ON progress_track.Progress_Report_Pupils_ID = pupils.Pupils_ID 
INNER JOIN referrer ON pupils.Pupils_Referrer = referrer.Referrer_ID; 

針對您的評論：

Could you please post this as an answer. It worked but it still did not show any data from the referrer table

• 如果連接條件不符合，那麼除非使用LEFT JOIN，否則無法看到 數據。請先檢查您的數據。
• 請確保您有符合這兩個條件的數據： progress_track.Progress_Report_Pupils_ID = pupils.Pupils_ID referrer.Referrer_ID = pupils.Pupils_Referrer

Answer 2

請刪除分號在第一內結束加入聲明。因爲，查詢嘗試在查詢本身的第一個分號後終止語句。所以，這是列Referrer_Name沒有引用表的原因：「referrer」。

原：

FROM pupils INNER JOIN progress_track ON progress_track.Progress_Report_Pupils_ID=pupils.Pupils_ID; INNER JOIN referrer ON pupils.Pupils_Referrer, referrer.Referrer_ID ;

使用此：

FROM pupils INNER JOIN progress_track ON progress_track.Progress_Report_Pupils_ID=pupils.Pupils_ID INNER JOIN referrer ON pupils.Pupils_Referrer = referrer.Referrer_ID ;