create table Students(StudentID int NOT NULL, primary key (StudentID), StudentName varchar(255), Grade varchar(255), class varchar(255));
1.插入数据，
insert into Students(StudentID,StudentName,Grade,class ) values (‘20150314',"Dubingjie","one","three");
2.更新数据，
select * from Students where class in (‘Two’,’three’);
update Students set class="Two" where StudentId=‘20150314’;
3.增加表字段，
alter table Students add Lessons char(255);
4.删除某行数据，
delete from Students where StudentID='20150316';
5.删除表，
drop table teachers;
6.order by排序
select * from Students order by Lessons;
7.distinct去重显示数据，
insert into Students(StudentID,StudentName,Grade,class ) values (‘20150317',"Dbj","one","three");
8.AND、OR进行查找，
select * from Students where (class='Two' or class='three') and Lessons='3';
9.IN操作，
select * from Students where class in (‘Two’,’three’);
10.Between方法，
select * from Students where StudentName between 'Bingjie' and 'Dbj';
11.内连接inner join.
select Students.StudentName,Teachers.TeacherName from Students inner join Teachers on Students.class=Teachers.class;
12.Alias假名
select Stu.StudentName,Teac.TeacherName from Students as Stu, Teachers as Teac where Stu.class=Teac.class;
13.left join 左连接
select Students.StudentName,Teachers.TeacherName,Students.class from Students left join Teachers on Students.class=Teachers.class order by Students.class;
14.right join 右连接
select Students.StudentName,Teachers.TeacherName,Students.class from Students right join Teachers on Students.class=Teachers.class order by Students.class;
15.备份一张表
create table Teachers_backup as( select * from Teachers );
16.复制表结构到另一张表中
insert into Teachers_backup select * from Teachers;
17.插入现在时间Now（）；
update Teachers_backup set class=Now() where TeacherID='201503140';
18.创建索引create index
create index index_name on Teachers(TeacherID);
19.查看索引
show index from Teachers;
20.删除索引
alter table Teachers drop index index_name;
21.建立视图view
create view my_view as select StudentName from Students;
22.日期函数
Now() curdate() date() date_Format()
23.NULL与0不等价，并且始终用IS NULL 来查找NULL的值
24.AVG,count,max,first函数运用
select AVG(number) from Teachers;
select count(number) from Teachers;
select first(number) from Teachers;
select sum(number) from Teachers;
select max(number) from Teachers;