1、查询1832班的成绩信息
mysql> select * from class where class=1832;
2,查询1833班,语文成绩大于80小于90的成绩信息
mysql> select * from class where class=1833 and chinese>80 and chinese<90;
3,查询学生表中5到10行的数据
mysql> select * from class where id limit 4,10;
4,显示1832班英语成绩为98,数学成绩为77的姓名与学号,
mysql> select id,name from class where class=1832 and math=77 and english=98;
5,查询出1832班成绩并且按语文成绩排序(降序)
mysql> select * from class where class=1832 order by chinese desc;
6,查询1833班与1832班,语文成绩与数学成绩都小于80的姓名。
mysql> select name from class where class in(1832,1833) and chinese<80 and math<80;
7,查询出没有参加语文考试的学生姓名和班级名称。
mysql> select name,class from class where chinese is null;
8,求出班上语文成绩不及格的学生姓名
mysql> select name from class where chinese<60 group by class;
9,求出每个班的数学平均成绩
mysql> select class,avg(math) from class group by class;
10、求出每个班级语文成绩总分 --涉及到每个的时候都需要分组
mysql> select class,sum(chinese) from class group by class;
11、将语文成绩不及格的学生成绩改为60分
mysql> update class set chinese=60 where chinese<60;
12、三科分数都大于70分的人名和年纪
mysql> select name,age from class where chinese>70 and math>70 and english>70;
13、求出英语分数高于70且其它任何一科目大于60分的人和班级
mysql> select name,class from class where english>70 and math>60 or chinese>60;
14、统计每个班的人数
mysql> select class,count(id) from class group by class;
15、求每个班数学成绩大于80的人数
mysql> select class,count(*) from class where math>80 group by class;
17、给student表增加3个字段(数据类型及长度自定义,建议要合理),
mysql> alter table class add(sex int(20),chemistry int(20),history int(20));