6.7.1.sql

清华大学出版社出版的数据库系统教程附带的实验教程中所有的源代码

(a)
EXEC sp_lock
GO

(b)
USE School
GO

SELECT sid, sname, grade
FROM STUDENTS as s1
WHERE grade is not NULL
      AND
      NOT EXISTS
	(SELECT *
	FROM STUDENTS as s2
	WHERE s1.grade<s2.grade AND s1.sname<>s2.sname
	)
GO