mysql索引index相關指令的詳細介紹

本文主要內容：

1. 顯示表中多有的索引show all index

2. 新增索引ADD INDEX， 新增唯一索引add unique index

3. 多列聯合添加索引,primary key

4. 關鍵字index vs key

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show all index

show index from  tb_name 例如：

show index from springdemo.blog;

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新增索引ADD INDEX， 新增唯一索引add unique index

ALTER TABLE `table` ADD INDEX `product_id` (`product_id`)

# 创建唯一索引alter table tb_name  add unique index  `unique_idsrc_caffeversion` (`id_src`, `caffe_version`)

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多列聯合索引，新增主鍵

#多列索引ALTER TABLE `table` ADD INDEX `index_name` (`col1`,`col2`)

# add primary key 添加主键ALTER TABLE `table_name` ADD PRIMARY KEY ( `column` )

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關鍵字index vs key

#在建立表的時候，這兩個關鍵字沒什麼差別，相當於同義詞

What are differences between Index v.s. Key in MySQL

CREATE TABLE tasks ( 
task_id INT UNSIGNED NOT NULL AUTO_INCREMENT, 
INDEX parent (parent_id), 
....# However I found a code using KEY instead of INDEX as following....KEY order_date (order_date) 
...

There’s no difference. They are synonyms.This was implemented for 
 compatibility with other database systems.

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