create table tb12(id int auto_increment primary key,name varchar(32),age int)engine=innodb default charset=utf8;

增insert into tb11(name,age) values('alex',12);insert into tb11(name,age) values('alex',12),('root',18);insert into tb12(name,age) select name,age from tb11;

删delete from tb12;delete from tb12 where id !=2delete from tb12 where id =2delete from tb12 where id > 2delete from tb12 where id >=2delete from tb12 where id >=2 or name='alex'

改update tb12 set name='alex' where id>12 and name='xx'update tb12 set name='alex',age=19 where id>12 and name='xx'

查select * from tb12;select id,name from tb12;select id,name from tb12 where id > 10 or name ='xxx';select id,name as cname from tb12 where id > 10 or name ='xxx';select name,age,11 from tb12;

where:select * from tb12 where id != 1select * from tb12 where id in (1,5,12);select * from tb12 where id not in (1,5,12);select * from tb12 where id in (select id from tb11)select * from tb12 where id between 5 and 12;通配符:数字用where id＝；where id not in,文字用where name like "张％"；where name="李平"select * from tb12 where name like "a%"select * from tb12 where name like "a_"

分页：select * from tb12 limit 10;select * from tb12 limit 0,10;select * from tb12 limit 10,10;select * from tb12 limit 20,10;select * from tb12 limit 10 offset 20;# page = input('请输入要查看的页码')# page = int(page)# (page-1) * 10# select * from tb12 limit 0,10; 1# select * from tb12 limit 10,10;2

排序：select * from tb12 order by id desc; 大到小select * from tb12 order by id asc;  小到大select * from tb12 order by age desc,id desc;取后10条数据select * from tb12 order by id desc limit 10;

分组：聚合函数select count(id),max(id),part_id from userinfo5 group by part_id;countmaxminsumavg**** 如果对于聚合函数结果进行二次筛选时？必须使用having ****select part_id from userinfo5 where part_id>10;select count(id),part_id from userinfo5 group by part_id having count(id) > 1;select count(id),part_id from userinfo5 where id > 10 group by part_id having count(id) > 1;

select * from userinfo5,department5select * from userinfo5,department5 where userinfo5.part_id = department5.idselect * from userinfo5 left join department5 on userinfo5.part_id = department5.idselect * from department5 left join userinfo5 on userinfo5.part_id = department5.id# userinfo5左边全部显示# select * from userinfo5 right join department5 on userinfo5.part_id = department5.id# department5右边全部显示select * from userinfo5 inner join department5 on userinfo5.part_id = department5.id将出现null时一行隐藏select * fromdepartment5left join userinfo5 on userinfo5.part_id = department5.idleft join userinfo6 on userinfo5.part_id = department5.idselectscore.sid,student.sidfromscoreleft join student on score.student_id = student.sidleft join course on score.course_id = course.cidleft join class on student.class_id = class.cidleft join teacher on course.teach_id=teacher.tidselect count(id) from userinfo5;获得表条数