我有一个问题，MySQL从平均水平上找到学生排名，我的排名是学号，所以如果学生的平均数相等，他们的排名将相同。
表格点
id | using_student_id | using_subject_id | total_point |
1 | 1 | 1 | 59 |
2 | 1 | 2 | 53 |
3 | 2 | 1 | 90 |
4 | 2 | 2 | 29 |
5 | 3 | 1 | 90 |
6 | 3 | 2 | 29 |
--------------------------------------------------------
表学生
----------------------------------------------------
id | name | id | sex | dob | class |
1 | sovann | G-000 001 | M | 1993-03-04 | 1 |
2 | rady ny| G-000 002 | M | 1992-01-05 | 1 |
3 | dy sove| G-000 003 | M | 1991-07-03 | 1 |
----------------------------------------------------
表主题
---------------------
id | name | class |
---------------------
1 | math | 1 |
2 | english| 1 |
---------------------
id | name |total| avg | rank |
1 | sovann | 112 | 56 | 1 |
2 | rady ny| 119 | 59.5 | 2 |
3 | dy sove| 119 | 59.5 | 2 |
---------------------------------
这是我试过的查询：
SELECT s.name as name, sum(p.total_point) as total, avg(p.total_point) as average,
CASE
WHEN @prevRank = avg(p.total_point) THEN @curRank
WHEN @prevRank := avg(p.total_point) THEN @curRank := @curRank + 1
END AS rank
from tbl_point as p
inner join tbl_student s
on p.uing_student_id = s.id
inner join tbl_subject as su
on su.id = p.using_subject_id,
(SELECT @curRank :=0, @prevRank := NULL) r
group by s.id
结果：
------------------------------------
name | total | average | rank | | rank
sovann | 112 | 56 | 1 | --> result should be| 2
rady ny| 119 | 59.5 | 2 | | 1
dy sove| 119 | 59.5 | 3 | | 1
------------------------------------
这是我的表：
-- Dumping structure for table student_db.tbl_class
CREATE TABLE IF NOT EXISTS `tbl_class` (
`id` int(11) NOT NULL AUTO_INCREMENT,
`name` varchar(45) DEFAULT NULL,
PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=4 DEFAULT CHARSET=utf8;
-- Dumping data for table student_db.tbl_class: ~3 rows (approximately)
/*!40000 ALTER TABLE `tbl_class` DISABLE KEYS */;
REPLACE INTO `tbl_class` (`id`, `name`) VALUES
(1, 'Class_one'),
(2, 'Class_two'),
(3, 'Class_three');
/*!40000 ALTER TABLE `tbl_class` ENABLE KEYS */;
-- Dumping structure for table student_db.tbl_point
CREATE TABLE IF NOT EXISTS `tbl_point` (
`id` int(11) NOT NULL AUTO_INCREMENT,
`total_point` float DEFAULT NULL,
`uing_student_id` int(11) NOT NULL,
`using_subject_id` int(11) NOT NULL,
PRIMARY KEY (`id`),
KEY `fk_tbl_point_tbl_student_idx` (`uing_student_id`),
KEY `fk_tbl_point_tbl_subject1_idx` (`using_subject_id`),
CONSTRAINT `fk_tbl_point_tbl_student` FOREIGN KEY (`uing_student_id`) REFERENCES `tbl_student` (`id`) ON DELETE NO ACTION ON UPDATE NO ACTION,
CONSTRAINT `fk_tbl_point_tbl_subject1` FOREIGN KEY (`using_subject_id`) REFERENCES `tbl_subject` (`id`) ON DELETE NO ACTION ON UPDATE NO ACTION
) ENGINE=InnoDB AUTO_INCREMENT=7 DEFAULT CHARSET=utf8;
-- Dumping data for table student_db.tbl_point: ~0 rows (approximately)
/*!40000 ALTER TABLE `tbl_point` DISABLE KEYS */;
REPLACE INTO `tbl_point` (`id`, `total_point`, `uing_student_id`, `using_subject_id`) VALUES
(1, 59, 1, 1),
(2, 53, 1, 2),
(3, 90, 2, 1),
(4, 29, 2, 2),
(5, 90, 3, 1),
(6, 29, 3, 2);
/*!40000 ALTER TABLE `tbl_point` ENABLE KEYS */;
-- Dumping structure for table student_db.tbl_student
CREATE TABLE IF NOT EXISTS `tbl_student` (
`id` int(11) NOT NULL AUTO_INCREMENT,
`name` varchar(45) DEFAULT NULL,
`student_id` varchar(50) DEFAULT NULL,
`sext` varchar(45) DEFAULT NULL,
`dob` date DEFAULT NULL,
`using_class_id` int(11) NOT NULL,
PRIMARY KEY (`id`),
KEY `fk_tbl_student_tbl_class1_idx` (`using_class_id`),
CONSTRAINT `fk_tbl_student_tbl_class1` FOREIGN KEY (`using_class_id`) REFERENCES `tbl_class` (`id`) ON DELETE NO ACTION ON UPDATE NO ACTION
) ENGINE=InnoDB AUTO_INCREMENT=4 DEFAULT CHARSET=utf8;
-- Dumping data for table student_db.tbl_student: ~0 rows (approximately)
/*!40000 ALTER TABLE `tbl_student` DISABLE KEYS */;
REPLACE INTO `tbl_student` (`id`, `name`, `student_id`, `sext`, `dob`, `using_class_id`) VALUES
(1, 'sovann', 'G-000 001', 'M', '1993-03-18', 1),
(2, 'rady ny', 'G-000 002', 'M', '1993-04-14', 1),
(3, 'dy sove', 'G-000 003', 'M', '1002-05-28', 1);
/*!40000 ALTER TABLE `tbl_student` ENABLE KEYS */;
-- Dumping structure for table student_db.tbl_subject
CREATE TABLE IF NOT EXISTS `tbl_subject` (
`id` int(11) NOT NULL AUTO_INCREMENT,
`name` varchar(45) DEFAULT NULL,
`using_class_id` int(11) NOT NULL,
PRIMARY KEY (`id`),
KEY `fk_tbl_subject_tbl_class1_idx` (`using_class_id`),
CONSTRAINT `fk_tbl_subject_tbl_class1` FOREIGN KEY (`using_class_id`) REFERENCES `tbl_class` (`id`) ON DELETE NO ACTION ON UPDATE NO ACTION
) ENGINE=InnoDB AUTO_INCREMENT=3 DEFAULT CHARSET=utf8;
-- Dumping data for table student_db.tbl_subject: ~2 rows (approximately)
/*!40000 ALTER TABLE `tbl_subject` DISABLE KEYS */;
REPLACE INTO `tbl_subject` (`id`, `name`, `using_class_id`) VALUES
(1, 'Math', 1),
(2, 'Egnlish', 1);