急高分请问MySQL查询有关问题
急!!!高分请教MySQL查询问题
现有表A和B
A表有一列bid允许为空,对应B表主键自增列
如果建视图的话,视图只会显示bid不为空的数据
A表bid为空的数据则显示不出
现在我想既有对应关系,又能显示A表bid为空的数据
只用一条语句,有办法实现么?该怎么写
- SQL code
<!-- Code highlighting produced by Actipro CodeHighlighter (freeware) http://www.CodeHighlighter.com/ --> 例如: 表A ----------------- id bid name 1 2 abc 2 def 3 1 ghi 表B ----------------- bid other 1 aaa 2 bbb 如果A的bid关联了B的bid 结果则为: ----------------- id bid name other 1 2 abc aaa 3 1 ghi bbb 以上 A表bid为空的列就没有了 现在我想要的结果则是: ----------------- id bid name other 1 2 abc aaa 2 def 3 1 ghi bbb
高分请教
------解决方案--------------------
去搜一下join left和join right我相信能够解决你的问题
------解决方案--------------------
select a.id,a.bid,a.name, b.other from A a left join B b on a.bid=b.bid;

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