我如何在一个表中添加两个表来输出 [英] How I Add Two Tables To Output In One Table

问题描述

我有两张桌子1和桌子。



table1

id name



table2

排名位置



i想输出一个表3

table3

id名称排名位置





以上两个表存在于数据库文件中，



i希望通过使用visual studio c＃

i have two tables table1 and table.

table1
id name

table2
rank postion

i want to output a table3
table3
id name rank position


the above two table exist in database file,

i want to create table3 in database by using visual studio c#

推荐答案

在数据库中创建table3。你不能处于当前状态。重新研究你的表格设计，回答这些问题：

1.每个表的主键是什么;

2. 2个表如何相关（链接） ，即主键< =>外键

参考： Relational_Database_Design [ ^ ]

You can't at the present state. Re-look into your tables design, answers these questions:
1. What is the primary key for each table;
2. How do the 2 tables related (linked), i.e. primary key <=> foreign key
Refer: Relational_Database_Design[^]

你的table2需要有一个外键id到表1.我不得不猜测你提供的有限信息表2有一个名为table1_id的字段。然后你可以这样做：

Your table2 needs to have a foreign key id to table 1. I would have to guess on the limited information you provided that table 2 has a field named something like table1_id. Then you can just do this:

SELECT table1.id, table1,name, table2.rank, table2.position
FROM table1 
LEFT JOIN table2 ON table1.id = table2.table1_id

您需要在表格之间建立关系，否则您最终会得到一些可能无意义数据的交叉连接。

You need to have a relationship between the tables or else you end up with some cross join that would likely be meaningless data.

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