六、MySQL的数据导入与导出

数据的导入与导出

目录

• 数据的导入与导出
  • 数据的导入操作
  • 数据的导出操作

• 查看导入与导出默认检索路径

  mysql> show variables like "%file%";			# 模糊查询
  mysql> show variables like "secure_file_priv";	# 精确路径查询
  
  mysql> system ls /var/lib/mysql-files			# 查看该目录
  
  # system 可以在mysql交互模式下执行系统命令
  

• 修改默认检索路径

  [root@admin ~]# mkdir /myload
  [root@admin ~]# chown mysql /myload
  
  [root@admin ~]# vim /etc/my.cnf
  [mysqld]
  secure_file_priv="/myload"
  secure_file_priv
  
  [root@admin ~]# systemctl restart mysqld
  
  mysql> show variables like "secure_file_priv";
  | secure_file_priv | /myload/ |
  

数据的导入操作

• 数据导入

  什么是数据导入: 把系统文件内容存储到数据库服务器的表里
  
  数据导入步骤
   - 默认只有root用户有数据导入权限
   - 建库 建表(表结构根据文件内容创建)
   - 导入数据
  
  命令格式
  mysql> load data infile "目录名/文件名" 
  into table 库名.表名 
  fields terminated by "分隔符" 		# 区分列
  lines terminated by "\n";		  # 区分行
  

• 数据导入示例

  mysql> create table user( username char(50), password char(1), uid int, gid int, comment varchar(150), homedir char(150), shell char(50));
  
  mysql> load data infile "/myload/passwd" into table user fields terminated by ":" lines terminated by "\n";
  
  mysql> select * from user;			# 查看导入结果
  
  mysql> alter table user add id int primary key auto_increment first; # 为该表添加一条id字段并设置为主键
  

数据的导出操作

• 数据导出

  什么是数据导出？把表记录保存到系统文件里
  
  命令格式
   select命令 into outfile "目录/文件名";
   select命令 into outfile "目录/文件名" fields terminated by "分隔符";
   select命令 into outfile "目录/文件名" fields terminated by "分隔符" lines terminated by "\n";
  
  # 目录只能是之前配置的检索目录
  

• 数据导出示例

  mysql> select * from user into outfile "/myload/1.txt";
  mysql> select * from user into outfile "/myload/2.txt" fields terminated by "<-->";
  mysql> select * from user into outfile "/myload/3.txt" fields terminated by "<-->" lines terminated by "\n";
  
  # 分别查看输出的三个文件，查看导出文件的区别
    - 不指定分隔符时，默认使用制表符
    - 好像有自动'\n'