备战2022春招或暑期实习，本专栏会持续输出MySQL系列文章，祝大家每天进步亿点点！文末私信作者，我们一起去大厂。
本篇总结的是 《如何查看MySQL数据库状态及信息》，后续会每日更新~
关于《Redis入门到精通》、《并发编程》、《Java全面入门》、《鸿蒙开发》等知识点可以参考我的往期博客
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目录
1、简介
2、正文
2.1 查看所有数据库
2.2 查看正在使用的数据库
2.3 查看当前数据库中的表
2.5 显示授权用户及其权限
2.6 查看服务器错误或警告信息
2.7 查看建库语句和建表语句
2.8 查看数据库端口
2.9 查看数据库索引大小
2.10 查看数据库大小
2.11 查看最大连接数
2.12 查看当前线程相关信息
2.13 查看文件存储路径
2.14 查看数据库编码
2.15 帮助指令
1、简介
现如今我们操作数据库，都是使用现成的数据库管理工具，比如Navicat、SQLyog等等。这些工具能够提供可视化操作界面，大大的提升了我们的操作效率，但是这样往往让我们忘却了很多数据库语句，比如建表语句、查询数据库信息等。这篇文章我们学习几个非常有用的语句，便于在没有可视化工具的时候给到你帮助。
2、正文
2.1 查看所有数据库
mysql> SHOW ERROES; ERROR 1064 (42000): You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'ERROES' at line 1 mysql> mysql> mysql> SHOW ERRORS; +-------+------+----------------------------------------------------------------------------------------------------------------------------------------------------------+ | Level | Code | Message | +-------+------+----------------------------------------------------------------------------------------------------------------------------------------------------------+ | Error | 1064 | You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'ERROES' at line 1 | +-------+------+----------------------------------------------------------------------------------------------------------------------------------------------------------+ 1 row in set (0.00 sec)
mysql> SHOW WARNINGS; +-------+------+------------------------------------------------------------------------------------------------------------------------------------------------------------+ | Level | Code | Message | +-------+------+------------------------------------------------------------------------------------------------------------------------------------------------------------+ | Error | 1064 | You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'WARRINGS' at line 1 | +-------+------+------------------------------------------------------------------------------------------------------------------------------------------------------------+ 1 row in set (0.00 s
mysql> SHOW CREATE TABLE user; +-------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+ | Table | Create Table | +-------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+ | user | CREATE TABLE `user` ( `id` bigint(20) NOT NULL AUTO_INCREMENT COMMENT '主键', `name` varchar(255) NOT NULL COMMENT '用户名', `age` int(11) NOT NULL COMMENT '年龄', `sex` smallint(6) NOT NULL COMMENT '性别', PRIMARY KEY (`id`) ) ENGINE=InnoDB DEFAULT CHARSET=utf8 | +-------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+ 1 row in set (0.01 sec)
mysql> SELECT CONCAT(((ROUND(SUM(data_length), 4) + ROUND(SUM(index_length), 4)) / (1024 * 1024)), ' mb') AS 'Database Size' -> FROM tables -> WHERE table_schema = 'liziba'; +---------------+ | Database Size | +---------------+ | 0.01562500 mb | +---------------+ 1 row in set (0.00 sec)
