mysql查询示例
use test;
create table t1(
tid smallint(5) unsigned auto_increment,
tname varchar(50),
tkecheng varchar(50),
tgrade smallint(10),
primary key(tid)
)ENGINE=innodb default charset=utf8;
INSERT into t1(tname,tkecheng,tgrade)
values('xm','yuwen',76),
('xm','shuxue',89),
('xm1','yuwen',73),
('xm1','shuxue',84),
('xm2','yuwen',72),
('xm2','shuxue',88),
('xm3','yuwen',70),
('xm3','shuxue',69),
('xm4','yuwen',69),
('xm4','shuxue',79),
('xm5','yuwen',76),
('xm5','shuxue',78),
('xm6','yuwen',84),
('xm6','shuxue',83),
('xm7','yuwen',76),
('xm7','shuxue',68),
('xm8','yuwen',84),
('xm8','shuxue',78),
('xm9','yuwen',76),
('xm9','shuxue',98),
('xm10','yuwen',84),
('xm10','shuxue',78),
('xm11','yuwen',86),
('xm11','shuxue',68);
commit;
select * from t1;
#1 数学成绩最高的前10条记录，按数学成绩降序排列
select * from t1 where t1.tkecheng='shuxue' order by t1.tgrade desc limit 10;
#2 查询所有科目都在80分以上记录
select * from t1 where t1.tgrade>=80;
s（sno，sn,sd,sa）sno，sn,sd,sa分别代表学号，学员姓名，班级，学员年龄
c（cno，cn）cno,cn分别代表课程编号，课程名称
sc（sno，cno,g）sno,cno,g分别代表学号，所选的课程编号，学习成绩
create table s(
sno smallint(5),
sn varchar(50),
sd varchar(50),
sa smallint(10)
)ENGINE=innodb default charset=utf8;
insert into s(sno,sn,sd,sa)
values(1001,'小明','班级1',24),
(1002,'小赵','班级1',22),
(1003,'小黄','班级2',23),
(1004,'小张','班级2',25),
(1005,'小李','班级3',23),
(1006,'小罗','班级3',22),
(1007,'小增','班级3',25);
commit;
create table c(
cno smallint(5),
cn varchar(50)
)ENGINE=innodb default charset=utf8;
insert into c(cno,cn)
values(9001,'功能测试'),
(9002,'自动化测试'),
(9003,'性能测试'),
(9004,'安全性测试'),
(9005,'体验性测试'),
(9006,'全栈测试');
commit;
create table sc(
sno smallint(5),
cno varchar(50),
g varchar(50)
)ENGINE=innodb default charset=utf8;
insert into sc(sno,cno,g)
values(1001,9001,78),
(1001,9002,68),
(1001,9003,84),
(1001,9004,62),
(1001,9005,98),
(1001,9006,89),
(1002,9001,68),
(1002,9002,64),
(1002,9003,83),
(1002,9004,63),
(1002,9005,90),
(1003,9003,68),
(1004,9004,99),
(1005,9005,99),
(1006,9001,69),
(1006,9002,67),
(1006,9003,86),
(1006,9004,87),
(1006,9005,90),
(1006,9006,91),
(1007,9001,99);
commit;
1)查询选修课程名称为‘性能测试’的学员学号和姓名？
select s.sno,s.sn from s,sc,c
where s.sno=sc.sno
and sc.cno=c.cno
and c.cn='性能测试';
2)查询选修课程超过5门的学员学号和所属班级？
select s.sno,s.sd from s
where s.sno
in (
select sc.sno
from c,sc
where c.cno=sc.cno
group by sc.sno
having count(*)>5
);
3)用户名为xuelei在2013-09-16和2013-09-17天插入的任务。
任务名包含"Arrow"，文件大小大于200
按文件由大到小排序，只提取出前5条数据
create table User_task(
Username varchar(50) comment '用户名',
Taskid int comment '任务id',
Taskname varchar(50) comment '任务名',
Task_filesize int comment '文件大小',
Insert_time datetime comment '插入日期'
)ENGINE=innodb default charset=utf8;
insert into User_task(Username,Taskid,Taskname,Task_filesize,Insert_time)
values('xuelei',1001,'Arrow is not a ',200,str_to_date('2013-09-15 09:00:00', '%Y-%m-%d %H:%i:%S')),
('xuelei',1002,'hao Arrow is not b ',201,str_to_date('2013-09-16 09:00:01', '%Y-%m-%d %H:%i:%S')),
('xuelei',1003,'cc Arrow is not c ',203,str_to_date('2013-09-17 09:01:00', '%Y-%m-%d %H:%i:%S')),
('xuelei',1004,'ddArrow is not d ',204,str_to_date('2013-09-18 09:00:02', '%Y-%m-%d %H:%i:%S')),
('xuelei',1005,'efArrow is not e ',203,str_to_date('2013-09-19 09:20:00', '%Y-%m-%d %H:%i:%S')),
('ceshi',2001,'agbrrow is not a ',203,str_to_date('2013-09-16 09:10:00', '%Y-%m-%d %H:%i:%S')),
('ceshi',2002,'brrow is not b ',203,str_to_date('2013-09-16 16:20:00', '%Y-%m-%d %H:%i:%S')),
('ceshi',2003,'brrow is not c ',203,str_to_date('2013-09-15 09:20:00', '%Y-%m-%d %H:%i:%S')),
('xuelei',2002,'Afrrow is not b ',303,str_to_date('2013-09-16 16:20:00', '%Y-%m-%d %H:%i:%S')),
('xuelei',2003,'arrow is not c ',303,str_to_date('2013-09-16 09:20:00', '%Y-%m-%d %H:%i:%S')),
('xuelei',3001,'Acrrow is not a ',200,str_to_date('2013-09-15 09:00:00', '%Y-%m-%d %H:%i:%S')),
('xuelei',3002,'AArrow is not b ',201,str_to_date('2013-09-16 09:00:01', '%Y-%m-%d %H:%i:%S')),
('xuelei',3003,'aaArrow is not c ',203,str_to_date('2013-09-17 09:01:00', '%Y-%m-%d %H:%i:%S')),
('xuelei',3004,'Arrow is not d ',204,str_to_date('2013-09-18 09:00:02', '%Y-%m-%d %H:%i:%S')),
('xuelei',3005,'Acrrow is not e ',203,str_to_date('2013-09-19 09:20:00', '%Y-%m-%d %H:%i:%S')),
('ceshi',4001,'brrow is not a ',203,str_to_date('2013-09-20 09:10:00', '%Y-%m-%d %H:%i:%S')),
('ceshi',4003,'brrow is not c ',203,str_to_date('2013-09-22 09:20:00', '%Y-%m-%d %H:%i:%S')),
('xuelei',5002,'Arrow is not b ',303,str_to_date('2013-09-23 16:20:00', '%Y-%m-%d %H:%i:%S')),
('xuelei',5003,'arrow is not c ',303,str_to_date('2013-09-24 09:20:00', '%Y-%m-%d %H:%i:%S')),
('xuelei',1011,'Arrow is not c ',201,str_to_date('2013-09-19 09:00:00', '%Y-%m-%d %H:%i:%S')),
('xuelei',1008,'arrow is not a ',199,str_to_date('2013-09-15 09:00:00', '%Y-%m-%d %H:%i:%S')),
('xuelei',1009,'arrow is not b ',200,str_to_date('2013-09-15 09:00:00', '%Y-%m-%d %H:%i:%S')),
('xuelei',1010,'arrow is not c ',201,str_to_date('2013-09-15 09:00:00', '%Y-%m-%d %H:%i:%S')),
('xuelei',1012,'Arrow is not b ',201,str_to_date('2013-09-15 23:59:59', '%Y-%m-%d %H:%i:%S')),
('xuelei',1013,'Arrow is not c ',201,str_to_date('2013-09-17 23:59:59', '%Y-%m-%d %H:%i:%S'));-
('xuelei',1014,'what is a Arrow is not c ',202,str_to_date('2013-09-17 23:59:59', '%Y-%m-%d %H:%i:%S'));
('xuelei',1015,' Arrow Arrow Arrow',203,str_to_date('2013-09-17 23:59:59', '%Y-%m-%d %H:%i:%S'));
commit;
select * from User_task ut
where ut.username='xuelei'
and INSTR(ut.Taskname,binary 'Arrow')<>0
and ut.task_filesize>200
and date_format(ut.insert_time,'%Y-%m-%d') between '2013-09-16' and '2013-09-17'
order by ut.task_filesize
desc limit 5;