本文介绍了在mysql中加入两个表?的处理方法,对大家解决问题具有一定的参考价值,需要的朋友们下面随着小编来一起学习吧!
问题描述
我有两个桌子
学生演示:
sid | date | status -------------------------------- 10 | 2013-12-28 | 1 11 | 2013-12-28 | 1 12 | 2013-12-28 | 1 13 | 2013-12-28 | 1 10 | 2013-12-30 | 1 11 | 2013-12-30 | 1 12 | 2013-12-30 | 1 13 | 2013-12-30 | 1spdemo:
date | status ------------------------ 2013-12-28 | cd 2013-12-29 | wd 2013-12-30 | cd使用查询
SELECT * FROM `studentdemo` RIGHT JOIN spdemo ON spdemo.date = studentdemo.date WHERE spdemo.date BETWEEN "2013-12-28" AND "2013-12-30"得出日期2013-12-29的空值:
NULL NULL NULL 2013-12-29 WD是否可以通过sid获得输出?
Is it possible to get an output with sid?
sid | date | status | date | status ------------------------------------------------------- 10 | null | null | 2013-12-29 | wd 11 | null | null | 2013-12-29 | wd 12 | null | null | 2013-12-29 | wd 13 | null | null | 2013-12-29 | wd推荐答案
您可以交叉联接以获取所有组合,然后将表LEFT JOIN移至该组合;
You could cross join to get all combinations, and LEFT JOIN the tables to that;
SELECT x.sid, table1.date, table1.status, x.date bdate, table2.status bstatus FROM (SELECT DISTINCT table1.sid, table2.date FROM table1 CROSS JOIN table2) x LEFT JOIN table1 ON x.sid=table1.sid AND x.date = table1.date LEFT JOIN table2 ON x.date=table2.date ORDER BY bdate, sid要测试的SQLfiddle .
更多推荐
在mysql中加入两个表?
发布评论