小编给大家分享一下MySQL快速查询的方法，相信大部分人都还不怎么了解，因此分享这篇文章给大家参考一下，希望大家阅读完这篇文章后大有收获，下面让我们一起去了解一下吧！
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mysql快速查询的方法：1、查询正在运行中的事务；2、查看当前连接，并且能够知晓连接数；3、查看一个表的大小；4、查看某个数据库所有表的大小。
mysql快速查询的方法：
1.查询正在运行中的事务
select p.id,p.user,p.host,p.db,p.command,p.time,i.trx_state,i.trx_started,p.info from information_schema.processlist p,information_schema.innodb_trx i where p.id=i.trx_mysql_thread_id;
2.查看当前连接，并且能够知晓连接数
select SUBSTRING_INDEX(host,‘:‘,1) as ip , count(*) from information_schema.processlist group by ip;
3.查看一个表的大小
select concat(round(sum(DATA_LENGTH/1024/1024),2),‘M‘) from information_schema.tables where table_schema=‘数据库名‘ AND table_name=‘表名‘;
4.查看某个数据库所有表的大小
select table_name,concat(round(sum(DATA_LENGTH/1024/1024),2),‘M‘) from information_schema.tables where table_schema=‘t1‘ group by table_name;
5.查看库的大小，剩余空间的大小
select table_schema,round((sum(data_length / 1024 / 1024) + sum(index_length / 1024 / 1024)),2) dbsize,round(sum(DATA_FREE / 1024 / 1024),2) freesize, round((sum(data_length / 1024 / 1024) + sum(index_length / 1024 / 1024)+sum(DATA_FREE / 1024 / 1024)),2) spsize from information_schema.tables where table_schema not in (‘mysql‘,‘information_schema‘,‘performance_schema‘) group by table_schema order by freesize desc;
6.查找关于锁
select r.trx_id waiting_trx_id,r.trx_mysql_thread_id waiting_thread,r.trx_query waiting_query,b.trx_id blocking_trx_id,b.trx_mysql_thread_id blocking_thread,b.trx_query blocking_query from information_schema.innodb_lock_waits w inner join information_schema.innodb_trx b on b.trx_id = w.blocking_trx_id inner join information_schema.innodb_trx r on r.trx_id = w.requesting_trx_id\G
information_schema的使用
1.查看各个库下的表数据大小
select table_name,concat(round(sum(DATA_LENGTH/1024/1024),2),‘M‘) from information_schema.tables where table_schema=‘db_name‘ group by table_name;
2.查看各个数据库的数据大小
select TABLE_SCHEMA, concat(round(sum(data_length)/1024/1024,2),‘ MB‘) as data_size from information_schema.tables group by table_schema;
3.查看实例有没有主键
select table_schema,table_name from information_schema.tables where (table_schema,table_name) not in(select distinct table_schema,table_name from information_schema.STATISTICS where INDEX_NAME=‘PRIMARY‘ ) and table_schema not in ( ‘sys‘,‘mysql‘,‘information_schema‘,‘performance_schema‘);
4.查看实例中哪些字段可以为null
select TABLE_SCHEMA,TABLE_NAME from COLUMNS where IS_NULLABLE=‘YES‘ and TABLE_SCHEMA not in (‘information_schema‘,‘performance_schema‘,‘mysql‘, ‘sys‘)\G
5.查看实例中有哪些存储过程和函数
#存储过程 select ROUTINE_SCHEMA,ROUTINE_NAME,ROUTINE_TYPE from information_schema.ROUTINES where ROUTINE_TYPE=‘PROCEDURE‘ and ROUTINE_SCHEMA not in (‘mysql‘,‘sys‘,‘information_schema‘,‘performance_schema‘); #函数 select ROUTINE_SCHEMA,ROUTINE_NAME,ROUTINE_TYPE from information_schema.ROUTINES where ROUTINE_TYPE=‘FUNCTION‘ and ROUTINE_SCHEMA not in (‘mysql‘,‘sys‘,‘information_schema‘,‘performance_schema‘);
6.查看实例中哪些表字段字符集和默认字符集不一致
select TABLE_SCHEMA,TABLE_NAME,COLUMN_NAME,CHARACTER_SET_NAME from information_schema.COLUMNS where (CHARACTER_SET_NAME is null or CHARACTER_SET_NAME <> ‘utf8‘) and TABLE_SCHEMA not in (‘information_schema‘,‘performance_schema‘,‘test‘,‘mysql‘,‘sys‘);
7.查看实例中哪些表字段字符校验规则和默认的不一致
查看当前字符集和校对规则设置
show variables like ‘collation_%‘; select TABLE_SCHEMA,TABLE_NAME,COLUMN_NAME,CHARACTER_SET_NAME,COLLATION_NAME from information_schema.COLUMNS where (COLLATION_NAME is null or COLLATION_NAME <> ‘utf8_general_ci‘) and TABLE_SCHEMA not in (‘information_schema‘,‘performance_schema‘,‘test‘,‘mysql‘,‘sys‘);
8.查看哪些账号有除了select、update、insert以外的权限
select GRANTEE,PRIVILEGE_TYPE,concat(TABLE_SCHEMA,‘-‘,TABLE_NAME,‘-‘,COLUMN_NAME) from COLUMN_PRIVILEGES where PRIVILEGE_TYPE not in (‘select‘,‘insert‘,‘update‘) union select GRANTEE,PRIVILEGE_TYPE,TABLE_SCHEMA from SCHEMA_PRIVILEGES where PRIVILEGE_TYPE not in (‘select‘,‘insert‘,‘update‘) union select GRANTEE,PRIVILEGE_TYPE,concat(TABLE_SCHEMA,‘-‘,TABLE_NAME) from TABLE_PRIVILEGES where PRIVILEGE_TYPE not in (‘select‘,‘insert‘,‘update‘) union select GRANTEE,PRIVILEGE_TYPE,concat(‘user‘) from USER_PRIVILEGES where PRIVILEGE_TYPE not in (‘select‘,‘insert‘,‘update‘);
9.查看实例中哪些表不是默认存储引擎，以默认存储引擎为innodb为例
select TABLE_NAME,ENGINE from information_schema.tables where ENGINE!=‘innodb‘ and TABLE_SCHEMA not in (‘information_schema‘,‘performance_schema‘,‘test‘,‘mysql‘, ‘sys‘);
10.查看实例中哪些表有外键
select a.TABLE_SCHEMA,a.TABLE_NAME,a.CONSTRAINT_TYPE,a.CONSTRAINT_NAME,b.REFERENCED_TABLE_NAME,b.REFERENCED_COLUMN_NAME from information_schema.TABLE_CONSTRAINTS a LEFT JOIN information_schema.KEY_COLUMN_USAGE b ON a.CONSTRAINT_NAME=b.CONSTRAINT_NAME where a.CONSTRAINT_TYPE=‘FOREIGN KEY‘;
11.查看实例中哪些表字段有级联更新
select TABLE_SCHEMA,TABLE_NAME,COLUMN_NAME,REFERENCED_TABLE_SCHEMA,REFERENCED_TABLE_NAME,REFERENCED_COLUMN_NAME from information_schema.KEY_COLUMN_USAGE where REFERENCED_TABLE_SCHEMA is not null and REFERENCED_TABLE_NAME is not null and REFERENCED_COLUMN_NAME is not null and table_schema not in (‘information_schema‘,‘performance_schema‘,‘test‘,‘mysql‘, ‘sys‘);
12.如何根据用户名、连接时间、执行的sql等过滤当前实例中的连接信息
select USER,HOST,DB from processlist where TIME>2;
13.查看数据库中没有索引的表
select TABLE_SCHEMA,TABLE_NAME from information_schema.tables where TABLE_NAME not in (select distinct(any_value(TABLE_NAME)) from information_schema.STATISTICS group by INDEX_NAME) and TABLE_SCHEMA not in (‘sys‘,‘mysql‘,‘information_schema‘,‘performance_schema‘);
14.查看数据库中有索引的表，建立了哪些索引
显示结果：库名、表名、索引名
select TABLE_SCHEMA,TABLE_NAME,group_concat(INDEX_NAME) from information_schema.STATISTICS where TABLE_SCHEMA not in (‘sys‘,‘mysql‘,‘information_schema‘,‘performance_schema‘) group by TABLE_NAME ;
以上是mysql快速查询的方法的所有内容，感谢各位的阅读！相信大家都有了一定的了解，希望分享的内容对大家有所帮助，如果还想学习更多知识，欢迎关注创新互联行业资讯频道！
