不要显示如果Count<2

Question

如果Working_On属性中的值低于2，我就试图隐藏和处理这些值。我尝试使用WHERE子句，但没有运气。我对MySQL很陌生。有人帮忙吗？

这是我使用的表格：

mysql> SELECT* 
       FROM employee_project;


+------+-------+---------------+
| eNum | pCode | date_assigned |
+------+-------+---------------+
| E246 | P123  | 2014-12-05    |
| E246 | P294  | 2013-11-21    |
| E387 | P123  | 2014-12-20    |
| E403 | P123  | 2015-04-15    |
| E403 | P332  | 2014-04-01    |
| E933 | P294  | 2013-11-21    |
| E933 | P332  | 2014-03-01    |
| E933 | P342  | 2014-12-20    |
+------+-------+---------------+



mysql> SELECT eNum, COUNT(pCOde) as Working_On 
       FROM employee_project 
       GROUP BY eNum;


    +------+------------+
    | eNum | Working_On |
    +------+------------+
    | E246 |          2 |
    | E387 |          1 |
    | E403 |          2 |
    | E933 |          3 |
    +------+------------+
    4 rows in set (0.00 sec)

Answer 1

下面的查询将帮助您

SELECT eNum, COUNT(pCOde) as Working_On 
   FROM employee_project 
   GROUP BY eNum;
   HAVING COUNT(pCOde) < 2; 

Answer 2

对此：

SELECT eNum, COUNT(pCOde) as Working_On 
   FROM employee_project 
   GROUP BY eNum;

添加以下内容：

having count(pCode) < 2

在group之后的子句。一些数据库引擎将允许您这样做：

having working_on < 2

但我不知道mySql是不是其中之一。

Answer 3

只需添加HAVING子句，它总是在聚合函数上执行：

   SELECT eNum, COUNT(pCOde) as Working_On 
   FROM employee_project 
   GROUP BY eNum;
   HAVING COUNT(pCode)<2