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

SELECTSUM(AVG_ROW_LENGTH*TABLE_ROWS+INDEX_LENGTH)/1024/1024 AS total_mbFROM information_schema.TABLES 

统计每个库大小：

SELECTtable_schema,SUM(AVG_ROW_LENGTH*TABLE_ROWS+INDEX_LENGTH)/1024/1024 AS total_mbFROM 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

selecttable_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.tablesgroup by table_schemaorder by sum(data_length) desc, sum(index_length) desc;

2.查看所有数据库各表容量大小

selecttable_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.tablesorder 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selecttable_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.tableswhere 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selecttable_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.tableswhere 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”