SQL命令错误

Question

我是SQL新手，有人可以回答我有什么问题？谢谢。

SELECT 
    bom.Parent_Material_Number, 
    mm.Material_Number, 
    mm.Material_Descr_HU, 
    bom.Child_Material_Number 
FROM mm,bom 
GROUP BY mm.Material_Descr_HU 

Answer 1

您的查询是错误的。如果您打算使用GROUP BY子句，请确保取消组合字段具有聚合，例如SUM(), MIN(), MAX(), etc。看到我的例子如下：

SELECT 
     MIN(bom.Parent_Material_Number), 
     MAX(mm.Material_Number), 
     mm.Material_Descr_HU, 
     MIN(bom.Child_Material_Number) 
FROM mm,bom 
WHERE bom.Parent_Material_Number = mm.Material_Number 
GROUP BY mm.Material_Descr_HU; 

你也可以显式加入。请看下图：

SELECT 
      MIN(bom.Parent_Material_Number), 
      MAX(mm.Material_Number), 
      mm.Material_Descr_HU, 
      MIN(bom.Child_Material_Number) 
    FROM mm INNER JOIN bom 
    ON bom.Parent_Material_Number = mm.Material_Number 
    GROUP BY mm.Material_Descr_HU; 

Answer 2

我看到你从两个表毫米和bomz FROM mm,bomz采取记录，并没有加入子句这一个在你的发言。

Answer 3

你需要一个JOIN或WHERE子句中的表连接在一起