下面可以通过聚合两数的结果来过速查询结果集的SOL子句是( )。
A. WHERE 子旬
B. GROUP BY子句
C. HAVING子句
D. ORDER BY子句
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若要求查找S表中,姓名的第一个字为王的学生学号和姓名。下面列出的SQL语句正确的是 ()。
A. SELECT Sno ,SNAME FROM S WHERE SNAME = '王%
B. SELECT Sno,SNAME FROM S WHERE SNAME LIKE‘王%’
C. SELECT Sno ,SNAME FROM S WHERE SNAME LIKE ’王_’
D. 全部正确
若要求“查询选修了3门以上课程的学生的学生号”,正确的SQL语句是( )。
A. SELECT Sno FROM SC GROUP BY Sno WHERE COUNT(*)>3
B. SELECT Sno FROM SC GROUP BY Sno HAVING( COUNT(*)> 3)
C. SELECT Sno FROM SC ORDER BY Sno WHERE COUNT(*)>3
D. SELECT Sno FROM SC ORDER BY Sno HAVING COUNT( *)>= 3
对下面的查询语句描述正确的是( )。SELECT StudentID,Name,(SELECT COUNT(*) FROM StudenExamWHERE StudenExam. StudentID=Student. StudentID AS ExamsTakenFROM StudentORDER BY ExamsTaken DESC
A. 从Student 表中查找StudentID和Name,并按照升序排列
B. 从Student表中查找StudentID和Name,并按照降序排列
C. 从Student表中查找StudentID、Name和考试次数
D. 从Student表中查找StudentID、Name井从StudenExam表中查找与StudentID一致的学生考试次数,并按照降序排列
在学生选课表(SC)中,查询选修20号课程(课程号CH)的学生的学号(XH) 及其成绩(GD)。查询结果按分数的降序排列。实现该功能,正确的SQL语句是()。
A. SELECT XH,CD FROM SC WHERE CH=’20’ ORDER BY GD DESC;
B. SELECT XH,CD FROM SC WHERE CH=’20’ ORDER BY GD ASC;
C. SELECT XH,CD FROM SC WHERE CH=’20' GROUP BY GD DESC;
D. SELECTXH CD FROM SC WHERE CH=’20’ GROUP BY GD ASC;
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