mysql - 需要 mysql 查询才能在单个查询中获取学生通过、失败和计数

Question

我有如下表格:

id    studentName   Marks

1        X           60

2        Y           25

3        Z           50

这里pass Marks是50分以上

我的输出应该是

id    studentName   Marks  status  totalCount

1        X           60     PASS       2

2        Y           25     FAIL       1

3        Z           50     PASS       2

此处通过的总数为 2，失败的总数为 1。

如何使用 MYSQL QUERY 完成此操作。

提前致谢....

Answer 1

SELECT A.id, A.studentName, A.Marks, B.status, B.totalStatus
FROM students AS A,
    (SELECT COUNT(1) AS totalStatus,
            IF(Marks>=50, 'PASS', 'FAIL') AS status
     FROM students
     GROUP BY IF(Marks>=50, 'PASS', 'FAIL')
     ) AS B
WHERE B.status = IF(A.Marks>=50, 'PASS', 'FAIL');

-- lwdba@localhost (DB test2) ::

CREATE TABLE students
(
id INT NOT NULL,
studentName VARCHAR(10),
Marks INT NOT NULL,
PRIMARY KEY (id)
);

-- Query OK, 0 rows affected (0.17 sec)
-- lwdba@localhost (DB test2) ::

INSERT INTO students VALUES
(1, 'X', 60),
(2, 'Y', 25),
(3, 'X', 50);

-- Query OK, 3 rows affected (0.06 sec)
-- Records: 3  Duplicates: 0  Warnings: 0

-- lwdba@localhost (DB test2) ::

SELECT A.id, A.studentName, A.Marks, B.status, B.totalStatus
FROM students AS A,
   (SELECT COUNT(1) AS totalStatus,
           IF(Marks>=50, 'PASS', 'FAIL') AS status
    FROM students
    GROUP BY IF(Marks>=50, 'PASS', 'FAIL')) AS B
WHERE B.status = IF(A.Marks>=50, 'PASS', 'FAIL');

+----+-------------+-------+--------+-------------+
| id | studentName | Marks | status | totalStatus |
+----+-------------+-------+--------+-------------+
|  1 | X           |    60 | PASS   |           2 |
|  2 | Y           |    25 | FAIL   |           1 |
|  3 | X           |    50 | PASS   |           2 |
+----+-------------+-------+--------+-------------+
3 rows in set (0.00 sec)