运行这个查询，你可能会得到你想要的:

SELECT table_schema "DB Name",
        ROUND(SUM(data_length + index_length) / 1024 / 1024, 1) "DB Size in MB" 
FROM information_schema.tables 
GROUP BY table_schema; 

这个查询来自mysql论坛，那里有更全面的说明可用。

要获得以MB为单位的结果:

SELECT
SUM(ROUND(((DATA_LENGTH + INDEX_LENGTH) / 1024 / 1024), 2)) AS "SIZE IN MB"
FROM INFORMATION_SCHEMA.TABLES
WHERE
TABLE_SCHEMA = "SCHEMA-NAME";

要获得GB的结果:

SELECT
SUM(ROUND(((DATA_LENGTH + INDEX_LENGTH) / 1024 / 1024 / 1024), 2)) AS "SIZE IN GB"
FROM INFORMATION_SCHEMA.TABLES
WHERE
TABLE_SCHEMA = "SCHEMA-NAME";

mysqldiskusage  --server=root:MyPassword@localhost  pics

+----------+----------------+
| db_name  |         total  |
+----------+----------------+
| pics     | 1,179,131,029  |
+----------+----------------+

如果没有安装，可以通过安装mysql-utils包来安装，大多数主要发行版都应该打包这个包。

可以使用下面的MySQL命令来确定

SELECT table_schema AS "Database", SUM(data_length + index_length) / 1024 / 1024 AS "Size (MB)" FROM information_schema.TABLES GROUP BY table_schema

结果

Database    Size (MB)
db1         11.75678253
db2         9.53125000
test        50.78547382

以GB为单位获取结果

SELECT table_schema AS "Database", SUM(data_length + index_length) / 1024 / 1024 / 1024 AS "Size (GB)" FROM information_schema.TABLES GROUP BY table_schema

如果你想要排序所有数据库大小的列表，你可以使用:

SELECT * 
FROM   (SELECT table_schema AS `DB Name`, 
           ROUND(SUM(data_length + index_length) / 1024 / 1024, 1) AS `DB Size in MB`
        FROM   information_schema.tables 
        GROUP  BY `DB Name`) AS tmp_table 
ORDER  BY `DB Size in MB` DESC; 

或者，如果使用phpMyAdmin，可以在数据库结构选项卡的页脚中查看表大小的总和。实际的数据库大小可能略大于这个大小，但它似乎与上面提到的table_schema方法一致。

的截图: