使用如下sql可查询当前用户所有表的行数以及大小：

SELECT 
  table_name,
  num_rows,
  TO_CHAR(last_analyzed, 'YYYY-MM-DD HH24:MI:SS') as last_analyzed,
  ROUND(num_rows * avg_row_len / 1024 / 1024, 2) as estimated_size_mb
FROM user_tables 
ORDER BY table_name;