多个多对多关系(循环关系) [英] Multiple Many-to-Many Relationships (Circular Relationship)
问题描述
好吧，我是编程人员的新手，主要是通过阅读站点来学习自己的知识....但是我正在寻找一个我在任何地方都找不到完整解释的答案.
OK, I'm new to programming things, mainly learned myself by reading sites.... but I'm looking for an answer I haven't found fully explained anywhere.
我在数据库中有三个表: - 部分 - 工具 -机器
I have three tables in a database: - Parts - Tools - Machines
我已经阅读了许多连接这三个表的两个联结表的实例，但这可以是循环的，并且我有三个联结表将三个信息表连接起来吗?
I have read many instances of two junction tables connecting these three tables, but can this be circular, and I have three junction tables connecting the three info tables?
这些都是多对多关系....例如:
These are all Many-to-Many relationships.... for example:
A部分和B部分均由工具1制成 A部分也由工具2制成 工具1可以安装在机器X，Y和Z中 A部分只能进入机器X和Z B部分只能进入X和Y机器
Part A and B are both made from Tool 1 Part A is also made from Tool 2 Tool 1 can fit in Machine X and Y and Z Part A can only go in Machine X and Z Part B can only go in machine X and Y
联结表的这种圆形"引用有效吗?
Does this "circular" reference of junction tables work?
我在想我需要一个: 零件到工具JCT 工具对机器JCT 机器对零件JCT
I'm thinking I need to have a: Part-to-Tool JCT Tool-to-Machine JCT Machine-to Part JCT
这是一个很好的圆形关系链接...我想我还没有找到任何在线显示此示例的示例.
This makes a nice round relationship link... and I guess I haven't found any examples showing this online anywhere.
任何帮助将不胜感激！
推荐答案
您需要设置如下表:
tblPart-零件A和B的记录
tblPart - records for parts A and B
tblTool-工具1和2的记录
tblTool - records for tools 1 and 2
tblMachine-机器X，Y和Z的记录
tblMachine - records for machines X, Y and Z
tblToolPart(字段:ToolId，PartId)-记录1，A； 1，B; 2，A.
tblToolPart (fields: ToolId, PartId) - records 1, A; 1, B; 2, A.
tblPartMachine(字段:PartId，MachineId)-记录A，X； A，Z; B，X; B，Y.
tblPartMachine (fields: PartId, MachineId) - records A, X; A, Z; B, X; B,Y.
tblMachineTool(字段:MachineId，PartId)-记录X，1; Y，1； Z，1.
tblMachineTool (fields: MachineId, PartId) - records X, 1; Y, 1; Z, 1.
不知道这是否足够清楚，无法理解这个主意，但是有了这6个表，您就可以开始构建查询以导入您感兴趣的任何关系.
Don't know if this is clear enough to get the idea over, but with these 6 tables you can begin building queries to import whatever relationships you're interested in.
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