mysql的索引创建、查看和删除

目录

单列索引

普通索引

唯一索引

主键索引

组合索引

全文索引

空间索引

---

单列索引

普通索引

create database mydb5;
use mydb5;

-- 方式1-创建表的时候直接指定
create  table student(
    sid int primary key,
    card_id varchar(20),
    name varchar(20),
    gender varchar(20),
    age int,
    birth date, 
    phone_num varchar(20),
    score double,
    index index_name(name) -- 给name列创建索引
);

-- 方式2-直接创建
-- create index indexname on tablename(columnname); 
create index index_gender on student(gender); 

-- 方式3-修改表结构(添加索引)
-- alter table tablename add index indexname(columnname)
alter table student add index index_age(age);

-- 1、查看数据库所有索引 
-- select * from mysql.`innodb_index_stats` a where a.`database_name` = '数据库名’; 
select * from mysql.`innodb_index_stats` a where a.`database_name` = 'mydb5';

-- 2、查看表中所有索引 
-- select * from mysql.`innodb_index_stats` a where a.`database_name` = '数据库名' and a.table_name like '%表名%’; 
select * from mysql.`innodb_index_stats` a where a.`database_name` = 'mydb5' and a.table_name like '%student%';

-- 3、查看表中所有索引 
-- show index from table_name; 
show index from student;


-- 4、删除索引
drop index index_gender on student 
-- 或 
alter table student drop index index_name

唯一索引

-- 方式1-创建表的时候直接指定
create  table student2(
    sid int primary key,
    card_id varchar(20),
    name varchar(20),
    gender varchar(20),
    age int,
    birth date, 
    phone_num varchar(20),
    score double,
    unique index_card_id(card_id) -- 给card_id列创建索引
);
-- 方式2-直接创建
-- create unique index 索引名 on 表名(列名) 
create unique index index_card_id on student2(card_id);

-- 方式3-修改表结构(添加索引)
-- alter table 表名 add unique [索引名] (列名)
alter table student2 add unique index_phone_num(phone_num)

--删除索引
drop index index_card_id on student2 
-- 或 
alter table student2 drop index index_phone_num

主键索引

组合索引

-- 创建索引的基本语法 
create index indexname on table_name(column1(length),column2(length)); 
-- 组合索引
use mydb5;
-- 创建索引的基本语法-- 普通索引
-- create index indexname on table_name(column1(length),column2(length)); 
create index index_phone_name on student(phone_num,name);
-- 操作-删除索引
 drop index index_phone_name on student; 
-- 创建索引的基本语法-- 唯一索引
create  unique index index_phone_name on student(phone_num,name); 

全文索引

-- 创建表的时候添加全文索引
create table t_article (
     id int primary key auto_increment ,
     title varchar(255) ,
     content varchar(1000) ,
     writing_date date -- , 
     -- fulltext (content) -- 创建全文检索
);

--数据准备
insert into t_article values(null,"Yesterday Once More","When I was young I listen to the radio",'2021-10-01');
insert into t_article values(null,"Right Here Waiting","Oceans apart, day after day,and I slowly go insane",'2021-10-02'); 
insert into t_article values(null,"My Heart Will Go On","every night in my dreams,i see you, i feel you",'2021-10-03');
insert into t_article values(null,"Everything I Do","eLook into my eyes,You will see what you mean to me",'2021-10-04');
insert into t_article values(null,"Called To Say I Love You","say love you no new year's day, to celebrate",'2021-10-05');
insert into t_article values(null,"Nothing's Gonna Change My Love For You","if i had to live my life without you near me",'2021-10-06');
insert into t_article values(null,"Everybody","We're gonna bring the flavor show U how.",'2021-10-07');

-- 修改表结构添加全文索引
alter table t_article add fulltext index_content(content)
 
-- 直接添加全文索引
create fulltext index index_content on t_article(content);

--使用全文索引
select * from t_article where match(content) against('yo’); -- 没有结果 单词数需要大于等于3 
select * from t_article where match(content) against('you'); -- 有结果

空间索引

create table shop_info (
  id  int  primary key auto_increment comment 'id',
  shop_name varchar(64) not null comment '门店名称',
  geom_point geometry not null comment '经纬度’,
  spatial key geom_index(geom_point)
);