数据库表的关联

 

查询两张表id相同的记录，显示姓名和分数：

1.

SELECT `student`.`name`,`stu_score`.`score`
FROM school.`student`,school.`stu_score`
WHERE student.`id`=stu_score.`id`

2. 

SELECT a.`name`,b.`score`
FROM school.`student` a,school.`stu_score` b
WHERE a.`id`=b.`id`

内连接

查询两张表id相同的记录，显示stu_score分数和student所有：

SELECT a.*,b.`score`
FROM school.`student` a INNER JOIN school.`stu_score` b
WHERE a.`id`=b.`id`

外连接

查询两张表id相同的记录，将student表格显示在stu_score左侧

SELECT *
FROM school.`student` a LEFT OUTER JOIN school.`stu_score` b
ON a.`id` = b.`id`