mysql中的information_schema.tables視圖

information_schema.tables視圖

desc  information_schema.TABLES
TABLE_SCHEMA    ---->庫名
TABLE_NAME      ---->表名
ENGINE          ---->引擎
TABLE_ROWS      ---->表的行數
AVG_ROW_LENGTH  ---->表中行的平均行（字節）
INDEX_LENGTH    ---->索引的佔用空間大小（字節）

查詢整個數據庫中所有庫和所對應的表信息

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

統計所有庫下的表個數

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

查詢所有innodb引擎的表及所在的庫

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

統計world數據庫下每張表的磁盤空間佔用

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

統計所有數據庫的總的磁盤空間佔用

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;"

生成整個數據庫下的所有表的單獨備份語句

模板語句：
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;                                   #查看所有數據庫
show tables;                                          #查看當前庫的所有表
show tables from  庫名                                #查看某個指定庫下的表
show create database 庫名                #查看建庫語句
show create table 庫名.表名                #查看建表語句
show  grants for  root@'localhost'       #查看用戶的權限信息
show  charset；                                   #查看字符集
show collation                                      #查看校對規則
show processlist;                                  #查看數據庫連接情況
show index from                                 #表的索引情況
show status                                         #數據庫狀態查看
SHOW STATUS LIKE '%lock%';         #模糊查詢數據庫某些狀態
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儲引擎
show engine innodb status\G               #查看InnoDB引擎相關的狀態信息
show binary logs                                    #列舉所有的二進制日誌
show master status                                 #查看數據庫的日誌位置信息
show binlog evnets in                             #查看二進制日誌事件
show slave status \G                             #查看從庫狀態
SHOW RELAYLOG EVENTS               #查看從庫relaylog事件信息
desc  (show colums from city)               #查看錶的列定義信息
mysql 官網
http://dev.mysql.com/doc/refman/5.7/en/show.html