共计 7133 个字符，预计需要花费 18 分钟才能阅读完成。
本文丸趣 TV 小编为大家详细介绍“Mysql 怎么查询数据库连接状态及连接信息”，内容详细，步骤清晰，细节处理妥当，希望这篇“Mysql 怎么查询数据库连接状态及连接信息”文章能帮助大家解决疑惑，下面跟着丸趣 TV 小编的思路慢慢深入，一起来学习新知识吧。
查看显示所有数据库
mysql show databases;
+--------------------+
| Database |
+--------------------+
| information_schema |
| INVOICE |
| mysql |
| performance_schema |
| test |
+--------------------+
5 rows in set (0.00 sec)
mysql查看当前使用的数据库
mysql select database();
+------------+
| database() |
+------------+
| INVOICE |
+------------+
1 row in set (0.00 sec)
mysql查看数据库使用端口
mysql show variables like port
+---------------+-------+
| Variable_name | Value |
+---------------+-------+
| port | 3306 |
+---------------+-------+
1 row in set (0.00 sec)查看当前数据库大小
例如，我要查看 INVOICE 数据库的大小，那么可以通过下面 SQL 查看
mysql use information_schema
Reading table information for completion of table and column names
You can turn off this feature to get a quicker startup with -A
Database changed
mysql select concat(round(sum(data_length)/(1024*1024),2) + round(sum(index_length)/(1024*1024),2), MB ) as DB Size
- from tables
- where table_schema= INVOICE
+-----------+
| DB Size |
+-----------+
| 7929.58MB |
+-----------+
1 row in set, 1 warning (0.00 sec)查看数据所占的空间大小
mysql use information_schema;
Reading table information for completion of table and column names
You can turn off this feature to get a quicker startup with -A
Database changed
mysql select concat(round(sum(data_length)/(1024*1024),2), MB ) as DB Size
- from tables
- where table_schema= INVOICE
+-----------+
| DB Size |
+-----------+
| 6430.26MB |
+-----------+
1 row in set, 1 warning (0.00 sec)
mysql查看索引所占的空间大小
mysql select concat(round(sum(index_length)/(1024*1024),2), MB ) as DB Size
- from tables
- where table_schema= INVOICE
+-----------+
| DB Size |
+-----------+
| 1499.32MB |
+-----------+
1 row in set, 1 warning (0.13 sec)
mysql查看数据库编码
mysql show variables like character%
+--------------------------+----------------------------+
| Variable_name | Value |
+--------------------------+----------------------------+
| character_set_client | utf8 |
| character_set_connection | utf8 |
| character_set_database | utf8 |
| character_set_filesystem | binary |
| character_set_results | utf8 |
| character_set_server | latin1 |
| character_set_system | utf8 |
| character_sets_dir | /usr/share/mysql/charsets/ |
+--------------------------+----------------------------+
8 rows in set (0.00 sec)character_set_client 为客户端编码方式；
character_set_connection 为建立连接使用的编码；
character_set_database 为数据库的编码；
character_set_results 为结果集的编码；
character_set_server 为数据库服务器的编码；
只要保证以上采用的编码方式一样，就不会出现乱码问题。
mysql show variables like collation%
+----------------------+-------------------+
| Variable_name | Value |
+----------------------+-------------------+
| collation_connection | utf8_general_ci |
| collation_database | utf8_general_ci |
| collation_server | latin1_swedish_ci |
+----------------------+-------------------+
3 rows in set (0.00 sec)status 也可以查看数据库的编码
mysql status;
--------------
mysql Ver 14.14 Distrib 5.6.20, for Linux (x86_64) using EditLine wrapper
Connection id: 1
Current database: INVOICE
Current user: root@localhost
SSL: Not in use
Current pager: stdout
Using outfile:
Using delimiter: ;
Server version: 5.6.20-enterprise-commercial-advanced MySQL Enterprise Server - Advanced Edition (Commercial)
Protocol version: 10
Connection: Localhost via UNIX socket
Server characterset: latin1
Db characterset: latin1
Client characterset: utf8
Conn. characterset: utf8
UNIX socket: /var/lib/mysql/mysql.sock
Uptime: 5 hours 18 min 51 sec
Threads: 1 Questions: 10884 Slow queries: 0 Opens: 650 Flush tables: 1 Open tables: 268 Queries per second avg: 0.568
--------------
mysql查看数据库的表信息
mysql show tables;
+---------------------------------------+
| Tables_in_information_schema |
+---------------------------------------+
| CHARACTER_SETS |
| COLLATIONS |
| COLLATION_CHARACTER_SET_APPLICABILITY |
| COLUMNS |
| COLUMN_PRIVILEGES |
| ENGINES |
| EVENTS |
| FILES |
| GLOBAL_STATUS |
| GLOBAL_VARIABLES |
| KEY_COLUMN_USAGE |
| OPTIMIZER_TRACE |
| PARAMETERS |
| PARTITIONS |
| PLUGINS |
| PROCESSLIST |
| PROFILING |
| REFERENTIAL_CONSTRAINTS |
| ROUTINES |
| SCHEMATA |
| SCHEMA_PRIVILEGES |
| SESSION_STATUS |
| SESSION_VARIABLES |
| STATISTICS |
| TABLES |
| TABLESPACES |
| TABLE_CONSTRAINTS |
| TABLE_PRIVILEGES |
| TRIGGERS |
| USER_PRIVILEGES |
| VIEWS |
| INNODB_LOCKS |
| INNODB_TRX |
| INNODB_SYS_DATAFILES |
| INNODB_LOCK_WAITS |
| INNODB_SYS_TABLESTATS |
| INNODB_CMP |
| INNODB_METRICS |
| INNODB_CMP_RESET |
| INNODB_CMP_PER_INDEX |
| INNODB_CMPMEM_RESET |
| INNODB_FT_DELETED |
| INNODB_BUFFER_PAGE_LRU |
| INNODB_SYS_FOREIGN |
| INNODB_SYS_COLUMNS |
| INNODB_SYS_INDEXES |
| INNODB_FT_DEFAULT_STOPWORD |
| INNODB_SYS_FIELDS |
| INNODB_CMP_PER_INDEX_RESET |
| INNODB_BUFFER_PAGE |
| INNODB_CMPMEM |
| INNODB_FT_INDEX_TABLE |
| INNODB_FT_BEING_DELETED |
| INNODB_SYS_TABLESPACES |
| INNODB_FT_INDEX_CACHE |
| INNODB_SYS_FOREIGN_COLS |
| INNODB_SYS_TABLES |
| INNODB_BUFFER_POOL_STATS |
| INNODB_FT_CONFIG |
+---------------------------------------+
59 rows in set (0.00 sec)或者使用下面 SQL 语句查看某个数据库的表信息。
select * from information_schema.tables where table_schema=‘databasename查看某种具体表的信息
select * from information_schema.tables where table_name =‘table_name查看数据库的所有用户信息
mysql select distinct concat(user: ,user, @ ,host,) as query from mysql.user;
+-------------------------------------+
| query |
+-------------------------------------+
| user: root @ 127.0.0.1 |
| user: root @ ::1 |
| user: root @ gettesx20.test.com |
| user: root @ localhost |
+-------------------------------------+
4 rows in set (0.00 sec)
mysql查看某个具体用户的权限
mysql show grants for root @ localhost
+---------------------------------------------------------------------------------------------------------------------------------+
| Grants for root@localhost |
+---------------------------------------------------------------------------------------------------------------------------------+
| GRANT ALL PRIVILEGES ON *.* TO root @ localhost IDENTIFIED BY PASSWORD *C7B1594FD74578DA3A92A61720AC67C6DBE6FC23 WITH GRANT OPTION |
| GRANT PROXY ON @ TO root @ localhost WITH GRANT OPTION |
+---------------------------------------------------------------------------------------------------------------------------------+
2 rows in set (0.00 sec)查看数据库的最大连接数
mysql show variables like %max_connections%
+-----------------+-------+
| Variable_name | Value |
+-----------------+-------+
| max_connections | 151 |
+-----------------+-------+
1 row in set (0.00 sec)
mysql查看数据库当前连接数，并发数。
mysql show status like Threads%
+-------------------+-------+
| Variable_name | Value |
+-------------------+-------+
| Threads_cached | 0 |
| Threads_connected | 1 |
| Threads_created | 1 |
| Threads_running | 1 |
+-------------------+-------+
4 rows in set (0.00 sec)Threads_cached : 代表当前此时此刻线程缓存中有多少空闲线程。
Threads_connected : 代表当前已建立连接的数量，因为一个连接就需要一个线程，所以也可以看成当前被使用的线程数。
Threads_created : 代表从最近一次服务启动，已创建线程的数量。
Threads_running : 代表当前激活的（非睡眠状态）线程数。并不是代表正在使用的线程数，有时候连接已建立，但是连接处于 sleep 状态，这里相对应的线程也是 sleep 状态。
查看数据文件存放路径
mysql show variables like %datadir%
+---------------+-------------------+
| Variable_name | Value |
+---------------+-------------------+
| datadir | /mysqldata/mysql/ |
+---------------+-------------------+
1 row in set (0.00 sec)
mysql读到这里，这篇“Mysql 怎么查询数据库连接状态及连接信息”文章已经介绍完毕，想要掌握这篇文章的知识点还需要大家自己动手实践使用过才能领会，如果想了解更多相关内容的文章，欢迎关注丸趣 TV 行业资讯频道。
正文完
![Frank#smith[Kfyzeiuqujbpygze,2,5]](https://cravatar.cn/avatar/ebd2642d86a4b40100d29dc76ec89b0d?s=96&d=monsterid&r=r)