本文主要內容：
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顯示表中多有的索引show all index
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添加索引ADD INDEX， 添加唯一索引add unique index
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多列聯合添加索引,primary key
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關鍵詞index vs key
show all index
show index from ?tb_name 例如：
show?index?from?springdemo.blog;
添加索引ADD INDEX， 添加唯一索引add unique index
ALTER?TABLE?`table`?ADD?INDEX?`product_id`?(`product_id`) #?創建唯一索引alter?table?tb_name??add?unique?index??`unique_idsrc_caffeversion`?(`id_src`,?`caffe_version`)
多列聯合索引，添加主鍵
#多列索引ALTER?TABLE?`table`?ADD?INDEX?`index_name`?(`col1`,`col2`) #?add?primary?key?添加主鍵ALTER?TABLE?`table_name`?ADD?PRIMARY?KEY?(?`column`?)
關鍵詞index vs key
在創建表的時候，這兩個關鍵詞沒什么區別，相當于同義詞
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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