mysql中的information_schema.tables视图

information_schema.tables视图

desc  information_schema.TABLES
TABLE_SCHEMA    ---->库名
TABLE_NAME      ---->表名
ENGINE          ---->引擎
TABLE_ROWS      ---->表的行数
AVG_ROW_LENGTH  ---->表中行的平均行（字节）
INDEX_LENGTH    ---->索引的占用空间大小（字节）

查询整个数据库中所有库和所对应的表信息

select table_schema,group_concat(table_name)
from  information_schema.tables
group  by table_schema;

统计所有库下的表个数

select table_schema,count(table_name)
FROM information_schema.TABLES
GROUP BY table_schema

查询所有innodb引擎的表及所在的库

select   table_schema,table_name,ENGINE FROM information_schema.`TABLES`
WHERE engine='innodb';

统计world数据库下每张表的磁盘空间占用

SELECT table_name,CONCAT((TABLE_ROWS*AVG_ROW_LENGTH+INDEX_LENGTH)/1024," KB")  AS size_KB
FROM information_schema.tables WHERE TABLE_SCHEMA='world';

统计所有数据库的总的磁盘空间占用

SELECT
TABLE_SCHEMA,
CONCAT(SUM(TABLE_ROWS*AVG_ROW_LENGTH+INDEX_LENGTH)/1024," KB") AS Total_KB
FROM information_schema.tables
GROUP BY table_schema;
mysql -uroot -p123 -e "SELECT TABLE_SCHEMA,CONCAT(SUM(TABLE_ROWS*AVG_ROW_LENGTH+INDEX_LENGTH)/1024,' KB') AS Total_KB FROM information_schema.tables GROUP BY table_schema;"

生成整个数据库下的所有表的单独备份语句

模板语句：
mysqldump -uroot -p123 world city >/tmp/world_city.sql
SELECT CONCAT("mysqldump -uroot -p123 ",table_schema," ",table_name," >/tmp/",table_schema,"_",table_name,".sql" )
FROM information_schema.tables
WHERE table_schema NOT IN('information_schema','performance_schema','sys')
into outfile '/tmp/bak.sh' ;

CONCAT("mysqldump -uroot -p123 ",table_schema," ",table_name," >/tmp/",table_schema,"_",table_name,".sql" )

 

show 命令

show  databases;                                   #查看所有数据库
show tables;                                          #查看当前库的所有表
show tables from  库名                                #查看某个指定库下的表
show create database 库名                #查看建库语句
show create table 库名.表名                #查看建表语句
show  grants for  root@'localhost'       #查看用户的权限信息
show  charset；                                   #查看字符集
show collation                                      #查看校对规则
show processlist;                                  #查看数据库连接情况
show index from                                 #表的索引情况
show status                                         #数据库状态查看
SHOW STATUS LIKE '%lock%';         #模糊查询数据库某些状态
SHOW VARIABLES                             #查看所有配置信息
SHOW variables LIKE '%lock%';          #查看部分配置信息
show engines                                       #查看支持的所有的存储引擎
show engine innodb status\G               #查看InnoDB引擎相关的状态信息
show binary logs                                    #列举所有的二进制日志
show master status                                 #查看数据库的日志位置信息
show binlog evnets in                             #查看二进制日志事件
show slave status \G                             #查看从库状态
SHOW RELAYLOG EVENTS               #查看从库relaylog事件信息
desc  (show colums from city)               #查看表的列定义信息
mysql 官网
http://dev.mysql.com/doc/refman/5.7/en/show.html