sql连接两个表 [英] sql join two table

问题描述

TABLE A >>用户名1 次测试 12 测试23 测试34 测试4表 B >>用户名地址1个地址12 地址24 地址3结果1 test1 address12 test2 地址23 测试34 test4 address3

谁能告诉我如何编写查询并获取上述结果，非常感谢！我试过加入，左右加入.结果一无所获.

解决方案

你可以在这两个表之间写左外连接最好的理解方法是查看下图

查询您的需求

SELECT A.uid, A.name, B.address FROM A LEFT JOIN B ON A.uid=B.uid

阅读这篇关于代码项目的原创文章会对您有很大帮助:.

TABLE A >>
uid name
1   test1
2   test2
3   test3
4   test4

TABLE B >>
uid address
1   address1
2   address2
4   address3

RESULT
1   test1   address1
2   test2   address2
3   test3
4   test4   address3

Can anyone show me how to write a query and fetch the result as above, Thanks very much! i have tried join, left and right join. all result nothing.

解决方案

You can write left outer join between this two tables Best way to understand is check the below image

Query for your requirement

SELECT A.uid, A.name, B.address FROM A LEFT JOIN B ON A.uid=B.uid 

Reading this original article on The Code Project will help you a lot: Visual Representation of SQL Joins.

Find original one at: Difference between JOIN and OUTER JOIN in MySQL.

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