六、MySQL的數據導入與導出

數據的導入與導出

目錄

• 數據的導入與導出
  • 數據的導入操作
  • 數據的導出操作

• 查看導入與導出默認檢索路徑

  mysql> show variables like "%file%";			# 模糊查詢
  mysql> show variables like "secure_file_priv";	# 精確路徑查詢
  
  mysql> system ls /var/lib/mysql-files			# 查看該目錄
  
  # system 可以在mysql交互模式下執行系統命令
  

• 修改默認檢索路徑

  [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/ |
  

數據的導入操作

• 數據導入

  什么是數據導入: 把系統文件內容存儲到數據庫服務器的表里
  
  數據導入步驟
   - 默認只有root用戶有數據導入權限
   - 建庫 建表(表結構根據文件內容創建)
   - 導入數據
  
  命令格式
  mysql> load data infile "目錄名/文件名" 
  into table 庫名.表名 
  fields terminated by "分隔符" 		# 區分列
  lines terminated by "\n";		  # 區分行
  

• 數據導入示例

  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;			# 查看導入結果
  
  mysql> alter table user add id int primary key auto_increment first; # 為該表添加一條id字段並設置為主鍵
  

數據的導出操作

• 數據導出

  什么是數據導出？把表記錄保存到系統文件里
  
  命令格式
   select命令 into outfile "目錄/文件名";
   select命令 into outfile "目錄/文件名" fields terminated by "分隔符";
   select命令 into outfile "目錄/文件名" fields terminated by "分隔符" lines terminated by "\n";
  
  # 目錄只能是之前配置的檢索目錄
  

• 數據導出示例

  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";
  
  # 分別查看輸出的三個文件，查看導出文件的區別
    - 不指定分隔符時，默認使用制表符
    - 好像有自動'\n'