Oracle查询库中记录数大于2千万的所有表
假如当前用户拥有select any table权限，则可以使用下列sql语句：
select table_name, num_rows from dba_tables t where t.owner = upper('hr') and num_rows > 20000000;
或
select table_name, num_rows from all_tables t where t.owner = upper('hr') and num_rows > 20000000;