MySQL/MariaDB SQL操作笔记

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1、修改表字段类型

alter table nodes modify column info varchar(200)

示例操作入下：

MariaDB [dbmanager]> alter table nodes modify column info varchar(200);Query OK, 0 rows affected (0.02 sec)               Records: 0  Duplicates: 0  Warnings: 0MariaDB [dbmanager]> desc nodes;+-----------+--------------+------+-----+---------------------+-------------------------------+| Field     | Type         | Null | Key | Default             | Extra                         |+-----------+--------------+------+-----+---------------------+-------------------------------+| id        | varchar(36)  | NO   | PRI | NULL                |                               || nodename  | varchar(20)  | YES  |     | NULL                |                               || ip        | varchar(20)  | YES  |     | NULL                |                               || username  | varchar(20)  | YES  |     | NULL                |                               || password  | varchar(20)  | YES  |     | NULL                |                               || os        | varchar(20)  | YES  |     | NULL                |                               || pubkey    | varchar(400) | YES  |     | NULL                |                               || role      | varchar(100) | YES  |     | NULL                |                               |                              || sn        | int(10)      | YES  |     | NULL                |                               || info      | varchar(200) | YES  |     | NULL                |                               || status    | int(10)      | YES  |     | NULL                |                               |                           |+-----------+--------------+------+-----+---------------------+-------------------------------+14 rows in set (0.01 sec)MariaDB [dbmanager]>

2、删除表字段

MariaDB [dbmanager]> alter table nodes drop column pubkey;Query OK, 0 rows affected (0.04 sec)Records: 0  Duplicates: 0  Warnings: 0MariaDB [dbmanager]>

3、备份数据库

mysqldump -h hostname -uroot -p dbname > /root/sql/bak.sql

示例操作

[root@hadron ~]# mysqldump -h master -uroot -p123456 dbmanager > /root/sql/bak.sql[root@hadron ~]# ll sql|grep bak.sql-rw-r--r-- 1 root root 25908 11月 28 09:34 bak.sql[root@hadron ~]#

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