查询所有数据库的总大小
方法如下：
mysql> use information_schema; mysql> select concat(round(sum(DATA_LENGTH/1024/1024),2),'MB') as data from TABLES; +-----------+ | data | +-----------+ | 3052.76MB | +-----------+ 1 row in set (0.02 sec)
统计一下所有库数据量
每张表数据量=AVG_ROW_LENGTH*TABLE_ROWS+INDEX_LENGTH
SELECT SUM(AVG_ROW_LENGTH*TABLE_ROWS+INDEX_LENGTH)/1024/1024 AS total_mb FROM information_schema.TABLES
统计每个库大小：
SELECT table_schema,SUM(AVG_ROW_LENGTH*TABLE_ROWS+INDEX_LENGTH)/1024/1024 AS total_mb FROM information_schema.TABLES group by table_schema;
第二种情况：查看指定数据库的大小，比如说：数据库test，方法如下：
mysql> use information_schema; mysql> select concat(round(sum(DATA_LENGTH/1024/1024),2),'MB') as data from TABLES where table_schema='test'; +----------+ | data | +----------+ | 142.84MB | +----------+ 1 row in set (0.00 sec)
1.查看所有数据库各容量大小
select table_schema as '数据库', sum(table_rows) as '记录数', sum(truncate(data_length/1024/1024, 2)) as '数据容量(MB)', sum(truncate(index_length/1024/1024, 2)) as '索引容量(MB)' from information_schema.tables group by table_schema order by sum(data_length) desc, sum(index_length) desc;
2.查看所有数据库各表容量大小
select table_schema as '数据库', table_name as '表名', table_rows as '记录数', truncate(data_length/1024/1024, 2) as '数据容量(MB)', truncate(index_length/1024/1024, 2) as '索引容量(MB)' from information_schema.tables order by data_length desc, index_length desc;
3.查看指定数据库容量大小
例：查看mysql库容量大小 select table_schema as '数据库', sum(table_rows) as '记录数', sum(truncate(data_length/1024/1024, 2)) as '数据容量(MB)', sum(truncate(index_length/1024/1024, 2)) as '索引容量(MB)' from information_schema.tables where table_schema='mysql';
4.查看指定数据库各表容量大小
例：查看mysql库各表容量大小 select table_schema as '数据库', table_name as '表名', table_rows as '记录数', truncate(data_length/1024/1024, 2) as '数据容量(MB)', truncate(index_length/1024/1024, 2) as '索引容量(MB)' from information_schema.tables where table_schema='mysql' order by data_length desc, index_length desc;
题外方法
直接用shell命令统计mysql data目录中的大小（注意只有库，不包含数据库日志大小）
备注 ：
data_length ：存储数据大小
data_length/1024/1024：将字节转换为MB
round(sum(data_length/1024/1024),2)：取两位小数
concat(round(sum(data_length/1024/1024),2),'MB') ：给计算结果追加单位 “MB”
