常用SQL语句总结

/**
*MySQL语句学习总结
*Author:bdzsl2013
*/
~~~~~~~数据库操作~~~~~~~
1、查看数据库
show databases;
2、选择数据库
use dbname;
3、创建数据库
create database dbname;
4、删除数据库
drop database dbname;
~~~~~~~~~表操作~~~~~~~~~
1、创建表
create table tbname (
	col1 type1 [not null] [primary key],
	col2 type2 ,
	...
	coln typen
);
2、查看表结构
describe tbname;
3、删除表
drop table tbname;
4、修改表名
alter table tbname rename newname;
5、增加列
alter table tbname add column colname coltype;
Tips:列增加后将不能删除
6、删除列
alter table tbname drop column colname;
7、修改列信息
alter table tbname change column colname name type;
~~~~~~~~~基本mysql语句~~~~~~~~~
1、选择
select * from tbname where constrainment(约束条件)
2、插入
insert into tbname(field1,field2) values(value1,value2);
3、删除
delete from tbname where constrainment(约束条件)
4、更新
update tbname set field1=value1 where constrainment(约束条件)
5、查找
select * from tbname where field1 like '%value%';(like语法)
6、排序
select * from tbname order by field1,field2[desc];
7、总数
select count(field1) as totalcount from tbname;
8、求和
select sum(field1) as sumvalue from tbname;
9、平均
select avg(field1) as avgvalue from tbname;
10、最大
select max(field1) as maxone from tbname;
11、最小
select min(field1) as minone from tbname;