主要来介绍下Inner Join , Full Out Join , Cross Join , Left Join , Right Join的区别。Inner Join：筛选两边都有的记录 Full Out Join：两边都筛选出来，匹配能匹配的，不能匹配的用NULL列出 Cross Join：列出两边所有组合，也称为笛卡尔集 A×B..
1.a. 并集UNION SELECT column1, column2 FROM table1 UNION SELECT column1, column2 FROM table2b. 交集JOIN SELECT * FROM table1 AS a JOIN table2 b ON a.name=b.namec. 差集NOT IN SELECT * FROM table1 WHERE name NOT IN(SELECT name FROM ..
