在 MySQL 中，如何获取特定数据库（或特定表）所占用的磁盘空间的大小？
统计库大小 | Database Size
How to get size of mysql database?
在通常情况下，数据表与数据索引会占用磁盘空间（其他部分可以忽略）：
// 统计 Databse 大小
SELECT table_schema AS "DB Name",
ROUND(SUM(data_length + index_length) / 1024 / 1024, 1) AS "DBinMB"
FROM information_schema.tables
GROUP BY table_schema
ORDER BY DBinMB DESC
LIMIT 30;
统计表大小 | Table Size
How to get the size of a table in MySQL
SELECT TABLE_NAME AS `Table`, ROUND((DATA_LENGTH + INDEX_LENGTH) / 1024 / 1024) AS `Size (MB)` FROM information_schema.TABLES WHERE TABLE_SCHEMA = "bookstore" ORDER BY (DATA_LENGTH + INDEX_LENGTH) DESC;