SQL语句入门

http://www.cnblogs.com/scorpioying/archive/2013/02/26/2933717.html

这篇文章里面的命令是mySQL的命令行，，部分命令如show databases等，在vb内不知如何执行。

create相关

show databases; 显示出现有的数据库 
use database_x; 现在要使用数据库database_x

show tables;

显示所有的表（注意：最后有个s）

show columns from coffee; 查看表结构
show create table coffee; 查看表信息，包括建表语句

create table coffee (id int(5) not null,coffee_name varchar(25)); 创建一张表，包含id和coffee_name两个字段

alter table student rename ss; 改变表名 
alter table coffee add taste varchar(10); 增加新的一列

alter table ss drop mark; 删除表ss中mark列

select语句

select * from coffee where id="1"; 查询出id=1的所有信息 
select coffee_name from coffee where id="2"; 查询出id=2的coffee name
 
select * from club where id between "1" and "3"; 查询出id=1到3的条目
select * from club where mark not between 48 and 50; 查询mark不在48与50之间的club
select * from club where id="1" or id="3"; 查询出id=1和id=3这两个条目 
select * from club where mark>50; 查询出mark大于50的club
 
select * from club where id in("1","3","4"); 查询id=1,3,4的条目 
select * from club where id not in("1","3","4");
 
select * from club where name like "M%r"; 通配符%表示任意长度的字符（可以是0，汉字为两个字符） 
select * from club where name like "M_r"; _表示单个字符
 
select * from club where id in("1","3","4") and mark>50; 多重查询
 
select * from club order by mark desc; 按照mark降序排列（desc：降序，usc：升序）

数量查询相关

select count(*) from club; 查询club中有多少条记录 
select count(distinct mark) from club; 不同分数的有多少条记录 
select sum(mark) from club; 积分总和 
select avg(mark) from club; 平均积分 
select max(mark) from club; 最高积分 
select min(mark) from club; 最低积分

update语句

update club set mark=mark-8 where id="1"; id=1的俱乐部积分罚8分

delete语句

delete from club where id="001"; 删除id=001的俱乐部信息

insert语句

insert into coffee (id,coffee_name,taste,rank) 
values ("1","BlueMountain","well","5");插入数据

insert into coffee (id,coffee_name,taste,rank) values
 ("1","BlueMountain","well","5"), ("2","Blue","well","5"); 插入多个数据