在日常工作中，会简单的使用一下mysql,故对常见命令操作总结一下，常用方式如下 

        1. mysqldump 命令的使用 

        备份和导出数据库 

        mysqldump -h database_ip -u Username -p --opt databasename > 

        backup-file.sql 

        只导出数据库表结构 

        mysqldump -h database_ip -d -u Username -p 

        databasename >database_structure.sql 

        只导出数据库中的某个表 

        mysqldump --opt --add-drop-table -u Username -p databasename 

        tablename > dump.sql 

        如果不想手工输入密码 请使用--password 参数 

        mysqldump -h database_ip -u Username --password=123456 --opt 

        databasename > backup-file.sql 

        mysqldump -h database_ip -d -u Username --password=123456 

        databasename >database_structure.sql 

        2. mysql 命令使用 

        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; 

        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 

        -00-00 00:00:00'; NOT NULL default '0000

        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;