**ThinkPHP ISNULL , ThinkPHP查询空或非空字段数据** ```sql ThinkPHP3.2 $where['age'] = array('exp',' is NULL'); $where['age'] = array('exp',' is not NULL'); ThinkPHP5.1 whereNull('level') whereNotNull('level') ``` **MySQL查找空字段或不为空的字段** MySQL查询空字段数据: ```sql select * from table where id = ''; select * from table where isnull(age); ``` **...