From the second grade to the ninth grade, the percentage of children who are bullied decreases.
举一反三
- 【单选题】5. 假定student表中有字段grade,grade代表分数,依次统计grade字段的最大值,最小值,平均值的SQL语句是 A. SELECT max(grade),min(grade),average(grade) FROM student; B. SELECT max(grade),min(grade),avg(grade) FROM student; C. SELECT min(grade),average(grade),max(grade) FROM student; D. SELECT min(grade),avg(grade),max(grade) FROM student;
- 针对表SC（sno, cno, grade），其中sno为学号，cno为课程号，grade为成绩。以下哪个操作（ ）统计出每位学生所选课程的最高分和最低分。 A: select sno,max(grade), min(grade) from sc B: select sno,max(grade), min(grade) from sc order by sno C: select sno,max(grade), min(grade) from sc group by sno D: select sno,avg(grade), sum(grade) from sc group by sno
- 已知关系模式：sc(sno,sname,grade)，各属性含义依次为学号、课程名、分数。要查找“数据库”课分数最高的学生的学号，正确的SQL语句是 A: SELECT sno FROM sc WHERE sname = "数据库" AND grade = MAX(grade) B: SELECT sno FROM sc FOR sname = "数据库" OR grade＞=MAX(grade) C: SELECT sno FROM sc WHERE sname = "数据库" AND grade = (SELECT MAX(grade) FROM sc) D: SELECT sno FROM sc FOR sname = "数据库" OR grade = (SELECT MAX(grade) FROM sc)
- 已知关系模式：SC(sno,sname,grade)，各属性含义依次为学号、课程名、分数。要查找“数据库”课分数最高的学生的学号，正确的SQL语句是( )。 A: SELECT sno FROM sc WHERE sname="数据库"AND grade=MAX(grade) B: SELECT sno FROM sc FOR sname="数据库"OR grade＞=MAX(grade) C: SELECT sno FROM sc WHERE sname="数据库"AND grade=(SELECT MAX(grade)FROM sc) D: SELECT sno FROM sc FOR sname="数据库"OR grade=(SELECT MAX(grade)FROM s
- 查询平均成绩小于70分的学生学号和平均成绩 A: SELECT Sno, AVG(grade) FROM SC GROUPBYSno B: SELECT Sno, AVG(grade) FROM SC GROUPBYSno HAVINGAVG(grade)<70; C: SELECT Sno, grade FROM SC GROUPBYSno HAVINGAVG(grade)<70;