ISSUE: MySQL空间量计算

MySQL所有数据库空间量计算: ``` select concat(truncate(sum(data_length)/1024/1024,2),' MB') as data_size from information_schema.tables; ``` 按照数据库分组计算: ``` select TABLE_NAME, concat(truncate(data_length/1024/1024,2),' MB') as data_size, concat(truncate(index_length/1024/1024,2),' MB') as index_size from information_schema.tables where TABLE_SCHEMA = 'TestDB' group by TABLE_NAME order by data_length desc; ```