找到至少参与过两个项目的所有员工

Question

表：ProjectRessources

IDPRoject  IDEmployee  NumHours   PricePerHr
1          1876       500        65
1          4354       2000       31
2          2231       250        55
3          2231       500        65
3          1212       3000       35
3          1876       2000       35

我只提出以下研究语法，但无法计算如何过滤仅指示2231和1876：

SELECT IDEmployee, COUNT (*) AS ‘Number of Projects’
FROM Projectressources
GROUP BY IDEmployee;

Answer 1

你朝着正确的方向前进。您遗失的部分是having子句，允许您过滤聚合表达式，例如count(*)：

SELECT   IDEmployee, COUNT (*) AS ‘Number of Projects’ 
FROM     Projectressources
GROUP BY IDEmployee
HAVING   COUNT(*) > 1 -- Here!