MySQL的常用命令集锦

将查询结果保存到文件

select title from book into outfile '/tmp/outfile.txt';

查找表中多余的重复记录，重复记录是根据某个字段（peopleId）来判断

select * from people where peopleId in (select peopleId from people group by peopleId having count(peopleId) > 1);

查询表中不重复记录(排除重复记录)

select * from phome_ecms_wma where title in (select distinct title from phome_ecms_wma);

删除表中重复记录,重复记录是根据某个字段（title）来判断

select *,count(distinct title) INTO OUTFILE '/tmp/table.bak' from phome_ecms_wma group by title; delete from phome_ecms_wma; LOAD DATA INFILE '/tmp/table.bak' REPLACE INTO TABLE phome_ecms_wma character set utf8;

随机选取记录

SELECT *FROM url ORDER BY RAND() LIMIT 5;

查询数据库当前编码

mysql> show variables like "character_set%";

修改表字段类型

mysql> alter table table_name change last_action last_action datetime NOT NULL default '0000-00-00 00:00:00';

给表添加一个新字段

mysql> ALTER TABLE host ADD ks_mac VARCHAR(100);

从表中删除一个字段

mysql> ALTER TABLE table_name DROP field_name;

重命名表

mysql>alter table t1 rename t2;

给字段加索引

mysql> alter table tablename add index 索引名 (字段名1[，字段名2 …]); mysql> alter table tablename add index emp_name (name);

加主关键字的索引

mysql> alter table tablename add primary key(id);

加唯一限制条件的索引

mysql> alter table tablename add unique emp_name2(cardnumber);

删除某个索引

mysql>alter table tablename drop index emp_name;

远程访问mysql 设置

mysql> GRANT ALL PRIVILEGES ON database_test.* to root@192.168.1.9 IDENTIFIED BY '123456'; mysql> FLUSH PRIVILEGES;

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