MySQL命令

（1）将查询结果保存到文件

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

（2）查找表中多余的重复记录（重复记录是根据某个字段来判断）

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

（3）查询表中不重复记录（排除重复记录）

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

（4）删除表中重复记录（重复记录是根据某个字段判断）

        select *,count(distinct title) into outfile '/tmp/table.bak' from phone group by title;

delete from phone;

       load data infile '/tem/table.bak' replace into table phone character set utf8;

（5）给表中添加一个字段

       alter table host add ks_mac varchar(100);

（6）删除一个字段

        alter table table_name delete field_name;

（7）重命名表

       alter table t1 rename t2；

（8）给字段加索引

       alter table table_name add index 索引名（字段1[, 字段2...]）;

（9）加主关键字的索引

     alter table table_name  add primary key(id);

（10）删除某个索引

      alter table table_name drop index emp_name;

（11）加唯一限制条件的索引

      alter table table_name add unique emp_name2(cardnumber);

（12）远程访问mysql设置

       grant all privileges on database_test .* to root@192.168.1.9 identified by "12345";

       flush privileges;

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