如何写才是最好SQL

[onlie]

如有两个表:
Student(学生信息表) 结构如下:
StudentId, Name, ClassId
/* 学生Id, 姓名, 班级Id */

FeeRecord(交费记录表) 结构如下
FeeRecordId, Title, Price, StudentId
/* 交费记录Id, 费用名称, 金额, 学生Id */

现在要做查询ClassId为99的所有学生交费记录,我写了两种方法
1.
SELECT *
FROM Student INNER JOIN FeeRecord
ON Student.StudentId = FeeRecord.StudentId AND Student.StudentId = 99

2.
SELECT *
FROM (SELECT * FROM Student WHERE ClassId = 99) AS Student
INNER JOIN FeeRecord ON Student.StudentId = FeeRecord.StudentId
以上两种方法,哪种执行效率更好,在我的实际工作中最多有五张表的连接,请朋友给个意见谢谢!!!

[ydage]

执行计划中,两者一样

[hxd001_810]

select *
from FeeRecord
where StudentId in (select StudentId from Student where ClassId = 99)

[lyh2919]

支持这种写法！！！！！
select *
from FeeRecord
where StudentId in (select StudentId from Student where ClassId = 99)

[wangdehao]

1.

[wangdehao]

看一下执行计划，也可能2个是一样的

[hyjsmeng]

看一下执行计划，然后进行设置索引来优化sql，例如在strudentid，classid上面就行