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  • mysql创建索引笔记

    1.添加PRIMARY KEY(主键索引。就是 唯一 且 不能为空。):

    ALTER TABLE `table_name` ADD PRIMARY KEY ( `column` ) 

    2.添加UNIQUE(唯一索引) :

    ALTER TABLE `table_name` ADD UNIQUE ( `column` ) 
     
    3.添加INDEX(普通索引) :
    ALTER TABLE `table_name` ADD INDEX index_name ( `column` )
     
    4.添加FULLTEXT(全文索引,是全文索引,用于在一篇文章中,检索文本信息的。) :
    ALTER TABLE `table_name` ADD FULLTEXT ( `column`) 
     
    5.添加多列索引:
    ALTER TABLE `table_name` ADD INDEX index_name ( `column1`, `column2`, `column3` )
     
    6,临时表使用

    create TEMPORARY table temp_1 like user
    create TEMPORARY table temp_2 like project

    insert into temp_1
    select * from (
    select * from user where usertype=8
    and uid not in (
    select uid from po_user) order by create_time desc) a

    insert into temp_2 select * from project where response_code in(
    select username from temp_1
    )

    insert into po_user(uid,pid,project_name,is_deleted,last_modify_time,last_modify_user)

    select uid,pid,project_name,1 as is_deleted,now() as last_modify_time,'手动修复数据' as last_modify_user from temp_1
    join temp_2 on temp_1.username =temp_2.response_code

    select * from po_user

     
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  • 原文地址:https://www.cnblogs.com/zd1994/p/7510910.html
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