Question

我一直在为作业创建数据库，我有一个需要实现的查询。查询需要提供具有两个以上更新补丁的所有项目的项目ID。我正在使用查询：

SELECT projectID
FROM Transaction
HAVING COUNT(Transaction.status = ‘patch’) > 2

但我从这个事件中得到projectID 1，但是只有两个以上补丁的唯一项目是9。

我正在使用该表：

CREATE TABLE Transaction
( 
    transactionID SMALLINT NOT NULL,
    ProjectID SMALLINT NOT NULL,
    PRIMARY KEY(transactionID, projectID),
    FOREIGN KEY(projectID) REFERENCES Project(projectID),
    userID SMALLINT NOT NULL,
    FOREIGN KEY(userID) REFERENCES Developer(userID),
    date DATE NOT NULL,
    status ENUM('upload','update','patch') NOT NULL
);

这是我在表格中的数据：

INSERT INTO Transaction
(transactionID, projectID, userID, date, status) values

(1,1,2,'2013-12-29','upload'),
(2,7,8,'2014-05-12','update'),
(3,9,20,'2013-07-15','patch'),
(4,12,8,'2013-08-04','upload'),
(5,10,26,'2014-11-06','update'),
(6,9,26,'2013-07-04','patch'),
(7,20,26,'2012-12-15','upload'),
(8,13,14,'2013-02-16','update'),
(9,12,8,'2014-07-11','patch'),
(10,19,20,'2013-08-14','upload'),
(11,19,20,2013-02-13,'update'),
(12,14,20,'2013-11-10','patch'),
(13,18,14,'2012-12-26','upload'),
(14,1,2,'2014-07-14','update'),
(15,12,8,'2013-04-11','patch'),
(16,3,14,'2013-09-16','upload'),
(17,4,20,'2013-09-02','update'),
(18,9,20,'2014-09-18','patch'),
(19,8,14,'2013-03-24','upload'),
(20,17,8,'2014-10-20','update');

有谁知道为什么这不起作用？

Answer 1

您缺少group by子句

group by projectid

SELECT projectID
   FROM Transaction
   where Transaction.status = 'patch'
   group by projectid
   HAVING COUNT(*) > 2

mySQL没有给出应该的结果

1 个答案: