我的SQL每次返回第一行，

Question

SELECT p.Producttype, pp.ProductID, r.Date1, r.Date2 
FROM customers AS c 
INNER JOIN orders AS r ON c.Cusid = r.Cusid 
INNER JOIN temporary AS temp ON r.Cusid = temp.Cusid 
INNER JOIN products AS pp ON pp.ProductID = temp.ProductID 
INNER JOIN Producttypes AS p ON p.Producttypeid = pp.Producttypeid 
WHERE temp.Cusid = '23' 
GROUP BY pp.ProductID 

請幫助我不知道自己能做什麼，該查詢返回每次第一行到日期1和date2

Answer 1

這是MySQL的一個已知的問題列。 它將允許組由沒有未分組字段的任意聚合函數。

它返回其默認行爲組，通過以外的所有領域的第一聚集。 看到這個：Why does MySQL allow "group by" queries WITHOUT aggregate functions?和Any reason for GROUP BY clause without aggregation function?

刪除Group By條款，你應該沒問題。

SELECT p.Producttype, pp.ProductID, r.Date1, r.Date2 
FROM customers AS c 
INNER JOIN orders AS r ON c.Cusid = r.Cusid 
INNER JOIN temporary AS temp ON r.Cusid = temp.Cusid 
INNER JOIN products AS pp ON pp.ProductID = temp.ProductID 
INNER JOIN Producttypes AS p ON p.Producttypeid = pp.Producttypeid 
WHERE temp.Cusid = '23' 
--GROUP BY pp.ProductID -->This should be removed as it causes to returne the first of each other field while keeping ProductID distinct in the returned table.