mysql基本数据库操作

Posted 2022-11-23 Airsolstice

1,将表中数据导出到文件中
eg:select * from tb_contact into outfile '/tmp/contact.txt' fields terminated by ',' optionally enclosed by '"' lines terminated by '\\n';


2,将文件数据导入到数据库表中(local关键字指定文件路径为客户机，默认为服务器路径)
eg:load data local infile '/tmp/contact.txt' into table tb_contact /*(contactId,id,groupName)*/ fields terminated by ',' lines terminated '\\r\\n';


3,数据库脚本整体备份
eg:mysqldump -uroot -p123 tb_contact > contact.dump;


4,mysqlimport导入数据
eg:mysqlimport -uroot -123 --local --columns=a,b,c db_test F:/contact.txt


5,防止SQL注入
a,表单的双向验证
b,对SQL错误进行自定义处理
c,对输入数据进行加密处理
d,使用存储过程加上权限控制来进行所有的查询
e,通过专业的漏洞检查工具来查找漏洞



6,对重复数据的忽略插入
eg:insert ignore into tb_contact values(4,2,"好友");


7,对重复数据的覆写插入
eg:replace into tb values(4,2,"好友");


8,统计某列的重复数据
eg:select count(*) as repet from tb_contact group by groupName having repet>1;


9,过滤重复的数据
eg:select distinct groupName/*指定不重复的列*/ from tb_contact oreder by groupName;


10,删除重复数据
eg:create tablt tmp select * from tb_contact group by group groupName;
   drop table tb_contact;
   alter table tmp rename to tb_contact;
   /*通过动态添加主键的方式消除重复的值*/
   alter table tb_contact add primary key (contactId); 


11,删除主键
eg:alter table tb_contact drop primary key; 


12,创建序列化表
eg:create table tb_contact(
id int not null auto_increment=100,
contactId int not null default 10000,
groupName varchar(50) not null,
primary key(id)
unique (contactId)
);




13,获取元数据
eg:select version();
   select user();
   select database();
   show status;
   show varlabes;


14,查询表结构
eg:show create table tb_contact;


15,创建临时表
eg:create termpoary table tmp(
id int not null primary key,
contactId int not null
);


16,增加/删除/修改字段
eg:alter table tb_contact drop id;
   alter table tb_contact add i int /*first第一列,after contactId 在某一列之后*/;
   alter table tb_contact modify i varchar(10) not null default 100;
   alter table tb_contact change i j varchar(10);
   alter table tb_contact change i i varchar(10);
   alter table tb_contact alter i set default 1000;
   alter table tb_contact alter i drop default;
   alter table tb_contact rename to tb_temp;


17,正则表达式的使用
eg:select * from tb_contact where groupName regexp 'ok$';


18,空置的使用
eg:select * from tb_contact where groupName is null;


19,内/左/右连接
eg:select * from tb_contact as a inner join tb_user as b on a.id = b.id;/*左右表互相匹配，两者同时存在的才显示，这与普通的where一样*/
   select * from tb_contact as a left join tb_user as b on a.id = b.id;/*左表全显，右表匹配左表，有则显示，无则显空*/
   select * from tb_contact as a right join tb_user as b on a.id = b.id;/*右表全显，左表匹配右表，有则显示，无则显空*/
 
20,数据分组
eg:select count(*) as rept from tb_contact group by groupName having rept>1;