學(xué)生表：
01.png
班級(jí)表：
02.png
1.內(nèi)連接查詢：查詢的結(jié)果為兩個(gè)表匹配到的數(shù)據(jù)
select * from students inner join classes on students.cls_id = classes.id;
03.png
2.左連接查詢：查詢的結(jié)果為兩個(gè)表匹配到的數(shù)據(jù)，左表特有的數(shù)據(jù)吹泡，對(duì)于右表中不存在的數(shù)據(jù)使用null
select * from students as s left join classes as c on s.cls_id = c.id;
04.png
3.右連接查詢：查詢的結(jié)果為兩個(gè)表匹配到的數(shù)據(jù)酪术，右表特有的數(shù)據(jù)器瘪，對(duì)于左表中不存在的數(shù)據(jù)使用null
select * from students as s right join classes as c on s.cls_id = c.id;
05.png
