Mysql

基本准备

cmd登录 mysql -rusername -ppassword
显示授权用户 show grants
创建数据库 create datebase datebase_name
展示所有数据库 show datebase
使用数据库 use database_name;
建表

    create table table_name(
    id int(11) auto_increment,
    name varchar(30),
    primary key(id)
    )default charset=utf8;

展示表 show tables
删表 drop table table_name
修改表 alter table table_name
重命名表 rename table table_name to table_name
展示列 show columns form table_name

查询

基本查询 select select * from table_name;
条件查询 select where select * from table_name where id = ?;
分页查询 select limit select * from table_name limit 0,5;
查询不同行 select distinct select distinct colunm_name from table_name;

修改

基本修改 update set where update table_name set column_name = value where id = ?

删除

基本删除 delete where delete from table_name where id = ?

插入

基本插入 insert into insert into table_name values(null,'');

插入多条数据

insert into table_name(column_name,
    column_name,
    column_name)
    VALUES(null,
        'b',
        'c'),
    values(null,
        null,
        'd');

排序

基本单列升序 select order by select column_name from table_name order by column_name
多列降序 select order by desc slect column_name,column_name from table_name order by column_name,column_name desc

过滤

基本过滤 where selcet * from table_name where id = ?
过滤空值 where is null select * from table_name where column_name is null
范围过滤 where between select * from table_name where column_name between a and b
和操作 selcet where and select * from table_name where column_name = a and column_name = b
或操作 select where or select * from table_name where column_name = a or column_name = b
条件范围 select where in(a,b) 且column_name为a或者b select * from table_name where column_name in (a,b)
否定 where not select * from table_name where column_name not in (a,b)
通配符 % _ like select * from table_name where colunm_name like '%a%' or column_name like '_a';

正则表达式

基本匹配 select regexp select * from table_name where column_name regexp 'reg'
Or匹配 select regexp | select * from table_name where column_name regexp 'a|b'
匹配几个字符之一 select regexp [] select * from table_name regexp '[123] a'
匹配范围 select regexp [-] select * from table_name where column_name regexp '[1-9] a'
匹配特殊字符 select regexp \ select * from table_name where column_name regexp '\\.'

计算字段

简介：在数据库服务器上完成不同表的列数据进行拼接，返回用户期待的数据，如：在地址表获得地址列，在联系表获得联系电话，两者拼接成收货信息，返会给用户
拼接字段 select Concat select Concat(column_name,'(',column_name,')')
去除空格 selct RTrim select Concat(RTrim(column_name),'(',RTrim(column_name),')')
重命名 select Concat as select Concat(column_name,'(',column_name,')') as column_name

基本函数

文本处理
日期时间
数值处理

聚集函数

avg()函数 select avg() as select avg(column_name) as colunm_name from table_name
count()函数 selct count() select count(column_name) from table_name
max()函数
min()函数
sum()函数
统计不同值 select avg distinct select avg(distinct column_name) from table_name
组合函数 select count(*) as colunm_name,min(colunm_name) as coulunm_name from table_name

分组数据

基本分组 select group by select column_name,count(*) from table_name group by column_name
分组过滤 select from where group by having count 返回12个月内具有两个订单以上的顾客，where过滤12个月，having过滤两个订单分组
```
select vend_id,count(*) as num_prods 
from products
where prod_price >= 10
group by vend_id
having count(*) >= 2;
```

子查询

基本嵌套先执行内嵌套 select from where in selcet

select column_name,column_name
from table_name
where id in (select id
            from table_name
            where num in (select num
                        from table_name
                        where id = 'a'));

关系表

相同数据出现多次决不是一件好事，此因素是关系数据库设计的基础。如：多个供应商与多个产品的关系，用三张表，vendors表存储所有供应商信息，每个供应商占一行，以ven_id为主键。products表存储所有产品信息以及供应商id，以pro_id为主键，通过pro_id的查询得到ven_id，从而在vendors表中找到供应商的信息，又称pro_id为vendors的外键。
外键：某个表中的一列，列值为另外一个表的主键。
1. 供应商信息不重复，不浪费时间空间
2. 供应商信息变更时，仅需更新供应商的单个记录
3. 数据无重复，数据一致处理更加简单

基本双表where内联结 select where table_name.column_name = table_name.column_name

select vend_name,prod_name,prod_price
from vendors,products
where vendors.vend_id = products.vend_id
order by vend_name,prod_name;

基本双表inner内联结 select inner join on table_name.column_name = table_name.column_name

    select vend_name,prod_name,prod_price
    from vendors
    inner join products
    on vendors.vend_id = products.vend_id

内连结查询可以代替嵌套子查询 selcet from where and

    select cust_name
    from customers,orders,orderitems
    where customers.order_num = orders.order_num
    and customers.cust_id = orders.cust_id
    and prod_id = 'tnt2';

表别名 select from where and as 实现在单一的select语句中多次引用同一张表

    select  p1.prod_id,p1.prod_name
    from products as p1,products as p2
    where p1.vend_id = p2.vend_id
    and p2.prod_id = 'dtntr';

外部联结 select from right outer join on 实现查询包括没有关联行的行，如未下单客户
```
select *
from customer right outer join orders
on oreders.cust_id = customers.cust_id
```

聚合函数联结

    select customers.cust_name
    count(orders.order_num) as num_ord
    from customers inner join orders
    on customers.cust_id = orders.cust_id
    group by customers.cust_id;

组合查询

基本组合查询 union

select vend_id,prod_id,prod_price
from products
where prod_price <= 5
union
select vend_id,prod_id,prod_price
from products
where vend_id in (1001,1002);

全文搜索

前置条件启用全文本搜索，需要建立MyISAM引擎的表ENGINE=MyISM，不同于一般的InnoDB表，并且在创建表时添加FULLTEXT子句FULLTEXT(note_text)

基本搜索 select from where Match Against

select note_text
from productnotes
where Match(note_text) Against('rabbit');

视图

基本介绍
1. 视图命名唯一
2. 不能索引，不能有关联的触发器和默认值
3. 可以和表一起联结使用
4. MySQL的select语句层次的封装，用于简化数据处理以及重新格式化基础数据或保护数据

创建视图 create view as select from where and

create view view_name as
select cust_name,prod_id
from customers,orders,orderitems
where customers.cust_id = order.cust_id
and orderitems.order_num = orders.order.order_num;

存储过程

基本介绍
1. 维护数据的一致性

执行存储过程

call productpricing(@pricelow,
                    @pricehigh,
                    @priceaverge);

创建存储过程使用//作结束符号。等效于";"

delimiter //
create procedure productpricing()
begin
    select avg(prod_price) as priceaverage
    from products;
end //

删除存储过程 drop procedure productpricing;

使用游标

使用触发器

基本准备
1. 唯一触发器名
2. 触发器关联的表
3. 触发器响应的活动
4. 触发器执行时机

创建触发器插入执行之后，将对每个插入的行显示一次

create trigger newproduct
after insert on products
for each row select 'Porduct added';

删除触发器 drop trigger newproduct
insert触发器 create trigger after insert on for each row new
```
create trigger neworder after insert on orders
for each row select new.order_num;
```
代码解读：插入一个新的订单到orders表时，MySQL生成一个新的订单号并保存到order_num中。触发器从NEW.order_num取得这个值并返回它。
delete触发器 create trigger before delete on for each row OLD delete触发器在delete语句执行之前或之后执行。在delete触发器代码内，你可以引用一个名为OLD的虚拟报表，访问被删除的行。
```
create trigger deleteorder before delete on orders
for each row
begin
    insert into archive_orders(order_num,order_date,cust_id)
    values(OLD.order_num,OLD.order_date,OLD.cust_id);
END;
```
代码解读：在任意订单被删除之前将执行此触发器，它使用一条insert语句将OLD中的值（被删除订单）保存到一个名为archive_orders的存档表中

事务

基础准备
1. 事务：指一组SQL语句
2. 回退：指撤销指定SQL语句的过程
3. 提交：指将为存储的SQL语句写入数据库表
4. 保留点：回退部分事务的标记点
回撤 start tansaction rollback
```
    selete * from ordertotals;
    start transaction;
    delete from ordertotals;
    select * from ordertotals;
    rollback;
    selete * from ordertotals;
```
代码解读：查询表，然后开启事务管理，用一条delete语句删除所有行，另一条selete语句验证表已空。再用一条rollback回退开启事务之前的所有语句

提交 start commit

    start transaction;
    delete from orders where order_num = 20010;
    delete from orders where order_num = 20021; 
    commit;

代码解读：若有一句执行失败，另一句也不会执行，只有两个句都成功执行，才会执行

设置保留点 savepoint delete1
使用保留点 rollback to delete1

备份

基本备份 "path\mysqldump.exe" -uusername -ppassword -hlocalhost -P3306 datebase_name -r path\test.sql

来源：oschina

链接：https://my.oschina.net/u/4270970/blog/4120183

标签

mysql

MyISAM

InnoDB

MySQL基础知识回顾