/ 2019-05-23
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8.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)
8.1 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;
8.2 统计所有库下的表个数
SELECT table_schema,COUNT(table_name)
FROM information_schema.TABLES
GROUP BY table_schema
8.3 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';
8.4 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';
8.5 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;"
8.6 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" )
8.7 107张表,都需要执行以下2条语句
ALTER TABLE world.city DISCARD TABLESPACE;
ALTER TABLE world.city IMPORT TABLESPACE;
SELECT CONCAT("alter table ",table_schema,".",table_name," discard tablespace")
FROM information_schema.tables
WHERE table_schema='world'
INTO OUTFILE '/tmp/dis.sql';
(2)