db_debug – TRUE/FALSE (boolean) – Whether database errors should be displayed. 需要设置db_debug = false Yes, this is the mysql_error() wrapper. $this->db->_error_message(); And the mysql_errno wrapper is: $this->db->_error_number(); via: http://stackoverflow.com/questions/3234564/under-codeigniter-is-it-possible-to-see-mysql-error
准备数据 SELECT uid, sum(count) FROM logs group by uid; hive> select * from logs; a 苹果 5 a 橙子 3 a 苹果 2 b 烧鸡 1 hive> SELECT uid, sum(count) FROM logs group by uid;……
准备数据 语句 select count, count(distinct uid) from logs group by count; hive> select * from logs; OK a 苹果 3 a 橙子 3 a 烧鸡 1 b 烧鸡 3 hive> select count, count(distinct uid)……