SQL 命令错误

Question

我是 SQL 的新手，有人可以回答我这是什么问题吗？！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

我看到您从两个表 mm 和 bomz FROM mm,bomz 中获取记录，并且在您的语句中没有针对此表的连接子句。

Answer 2

您的查询有误。如果您打算使用 GROUP BY 子句，请确保取消分组字段具有聚合，例如 SUM(), MIN(), MAX(), etc。请参阅下面的示例：

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;

您也可以显式加入。见下文：

    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 3

您需要一个 JOIN 或 WHERE 子句来 link 这些表

SQL 命令错误

SQL Command Error

mysql

select