1 )根据表查询平均成绩大于等于 60 分的同学的学生编号和学生姓名和平均成绩 2 )根据表查询在 SC 表存在成绩的学生信息 实验数据: 学生表: create table Student( Sid varchar(6), Sname varchar(10), Sage datetime, Ssex varchar(10)); insert into Student values('01' , ' ' , '1990-01-01' , ' 男 '); insert into Student values('02' , ' 钱电 ' , '1990-12-21' , ' 男 '); insert into Student values('03' , ' 风 ' , '1990-05-20' , ' 男 '); insert into Student values('04' , ' 云 ' , '1990-08-06' , ' 男 '); insert into Student values('05' , ' 梅 ' , '1991-12-01' , ' 女 '); insert into Student values('06' , ' 兰 ' , '1992-03-01' , ' 女 '); insert into Student values('07' , ' ' , '1989-07-01' , ' 女 '); insert into Student values('08' , ' 菊 ' , '1990-01-20' , ' 女 ') 成绩表 create table SC( Sid varchar(10), Cid varchar(10), score decimal(18,1)); insert into SC values('01' , '01' , 80); insert into SC values('01' , '02' , 90); insert into SC values('01' , '03' , 99); insert into SC values('02' , '01' , 70); insert into SC values('02' , '02' , 60); insert into SC values('02' , '03' , 80); insert into SC values('03' , '01' , 80); insert into SC values('03' , '02' , 80); insert into SC values('03' , '03' , 80); insert into SC values('04' , '01' , 50); insert into SC values('04' , '02' , 30); insert into SC values('04' , '03' , 20); insert into SC values('05' , '01' , 76); insert into SC values('05' , '02' , 87); insert into SC values('06' , '01' , 31); insert into SC values('06' , '03' , 34); insert into SC values('07' , '02' , 89); insert into SC values('07' , '03' , 98) 课程表 create table Course( Cid varchar(10), Cname varchar(10), Tid varchar(10)); insert into Course values ('01' , ' 语文 ' , '02'); insert into Course values ('02' , ' 数学 ' , '01'); insert into Course values ('03' , ' 英语 ' , '03') 教师表 create table Teacher( Tid varchar(10), Tname varchar(10)); insert into Teacher values ('01' , ' 张三 '); insert into Teacher values ('02' , ' 四 '); insert into Teacher values ('03' , ' 五 ')