mysql-索引
时间：2021-07-01 10:21:17
帮助过：32人阅读
key()，主键索引primary
key(),
联合索引，全文索引；
注意：主键索引不能为空，唯一索引可以为空
建立索引,
语法：
create table table_name(
列定义 primary key,
...
)
create table table_name(
列定义
primary key(字段名)/
index()
)
alter table table_name add unique key(index_name);
联合索引:
create table firewall(
host varchar(34) not
null,
port smallint(3) not
null,
access enum(‘deny‘,‘allow‘) not
null,
primary key(host,
port)
)
删除索引：alter table或者drop index,
格式：
drop index index_name on table_name;
alter table table_name drop index index_name;
alter table table_name drop primary key;
复制表数据like，如：create table gg_goods like ecs_goods;
蠕虫复制：insert into gg_goods(goods_name,shop_price) select goods_name,
shop_price from ecs_goods;
insert into gg_goods(goods_name,shop_price) select goods_name,
shop_price from gg_goods;
创建视图：select goods_id,goods_name,shop_price from ecs_goods a
join ecs_category b on a.cat_id=b.
cat_id;
create view vvgoods as select goods_id,goods_name,shop_price from ecs_goods a
join ecs_category b on a.cat_id=b.
cat_id;
select *
from vvgoods;
修改视图，重写一次；
视图和表的关系：表数据的改变会影响视图的结果；视图的改变不一定对表有影响
mysql-索引
标签：uniq alter access key 修改 enum char category code
