MySQL query to create a pivot table by joining 4 different table

Question

I have 4 mySQL tables namely Exams, Marks, Student and Subject. Sql with data is provided below. I need the output like below screenshot.

Marks is calculated from all Marks added together for the particular subject and student pair with their proper Weightage in Percentage (Exams with 0 Weightage are ignored)

I tried using the below query but the result didn't gave the cumulative marks so need help.

SET @sql = NULL;
SELECT
  GROUP_CONCAT(DISTINCT
               CONCAT('MAX(IF(sj.SubjectId = ''', SubjectId,''', pa.Marks, NULL)) AS ',SubjectId)
              ) INTO @sql
FROM Subject;

SET @sql = CONCAT('SELECT s.ID, s.StudentID, s.FirstName, s.LastName, ', @sql, ' 
                  FROM Student s
                  JOIN Marks AS pa 
                  ON pa.StudentID = s.StudentID AND pa.OrganizationId = s.OrganizationId 
                  JOIN Exams p
                  ON p.ExamId = pa.ExamId AND p.OrganizationId = pa.OrganizationId
                  JOIN Subject sj
                  ON p.SubjectId = sj.SubjectId AND pa.OrganizationId = sj.OrganizationId
                  WHERE p.Weightage > 0
                  GROUP BY s.ID');

PREPARE stmt FROM @sql;
EXECUTE stmt;

Please help. FIDDLE LINK


CREATE TABLE `Exams` (
  `ID` int(6) NOT NULL,
  `ExamId` varchar(20) COLLATE utf8_unicode_ci NOT NULL,
  `Name` varchar(50) COLLATE utf8_unicode_ci NOT NULL,
  `Date` datetime(6) DEFAULT NULL,
  `TotalMarks` int(6) NOT NULL,
  `SubjectId` varchar(30) COLLATE utf8_unicode_ci NOT NULL,
  `Weightage` int(6) NOT NULL DEFAULT '0',
  `OrganizationId` int(6) NOT NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci;

--
-- Dumping data for table `Exams`
--

INSERT INTO `Exams` (`ID`, `ExamId`, `Name`, `Date`, `TotalMarks`, `SubjectId`, `Weightage`, `OrganizationId`) VALUES
(8, 'EX_0001', 'Test 1', '2020-05-30 17:15:38.000000', 50, 'SUB_0002', 0, 116),
(9, 'EX_0002', 'Test 2', '2020-05-17 17:15:19.000000', 30, 'SUB_0001', 0, 116),
(10, 'EX_0003', 'Test 3', '2020-05-17 17:15:51.000000', 30, 'SUB_0003', 10, 116),
(11, 'EX_0004', 'Test 45', '2020-05-19 15:15:08.000000', 30, 'SUB_0001', 0, 116),
(12, 'EX_0005', 'Final Exam', '2020-05-20 15:30:53.000000', 100, 'SUB_0001', 80, 116),
(13, 'EX_0006', 'Terminal 3', '2020-05-20 15:30:03.000000', 50, 'SUB_0001', 10, 116);

-- --------------------------------------------------------

--
-- Table structure for table `Marks`
--

CREATE TABLE `Marks` (
  `ID` int(11) NOT NULL,
  `StudentId` varchar(30) COLLATE utf8_unicode_ci NOT NULL,
  `ExamId` varchar(30) COLLATE utf8_unicode_ci NOT NULL,
  `Marks` int(6) NOT NULL,
  `OrganizationId` int(6) NOT NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci;

--
-- Dumping data for table `Marks`
--

INSERT INTO `Marks` (`ID`, `StudentId`, `ExamId`, `Marks`, `OrganizationId`) VALUES
(14, 'S_100000001', 'EX_0004', 30, 116),
(15, 'S_100000001', 'EX_0003', 25, 116),
(16, 'S_100000001', 'EX_0002', 77, 116),
(17, 'S_100000003', 'EX_0003', 15, 116),
(18, 'S_100000003', 'EX_0004', 12, 116),
(19, 'S_100000003', 'EX_0001', 12, 116),
(20, 'S_100000002', 'EX_0004', 20, 116),
(21, 'S_100000002', 'EX_0003', 21, 116),
(22, 'S_100000001', 'EX_0005', 80, 116),
(23, 'S_100000002', 'EX_0005', 90, 116);

-- --------------------------------------------------------

--
-- Table structure for table `Student`
--

CREATE TABLE `Student` (
  `ID` int(6) NOT NULL,
  `GradeId` varchar(10) COLLATE utf8_unicode_ci DEFAULT NULL,
  `StudentID` varchar(30) COLLATE utf8_unicode_ci DEFAULT NULL,
  `OrganizationId` int(6) DEFAULT NULL,
  `FirstName` varchar(30) CHARACTER SET utf8 COLLATE utf8_unicode_ci DEFAULT NULL,
  `LastName` varchar(30) CHARACTER SET utf8 COLLATE utf8_unicode_ci DEFAULT NULL,
  `FatherFirstName` varchar(30) COLLATE utf8_unicode_ci DEFAULT NULL,
  `FatherLastName` varchar(30) CHARACTER SET utf8 COLLATE utf8_unicode_ci DEFAULT NULL,
  `DateOfBirth` varchar(30) COLLATE utf8_unicode_ci DEFAULT NULL,
  `PlaceOfBirth` varchar(30) COLLATE utf8_unicode_ci DEFAULT NULL,
  `Sex` varchar(30) COLLATE utf8_unicode_ci DEFAULT NULL,
  `Carnet` varchar(30) COLLATE utf8_unicode_ci DEFAULT NULL,
  `MobilePhone` bigint(8) DEFAULT NULL,
  `Address` varchar(60) COLLATE utf8_unicode_ci DEFAULT NULL,
  `MotherFirstName` varchar(30) CHARACTER SET utf8 COLLATE utf8_unicode_ci DEFAULT NULL,
  `MotherLastName` varchar(30) CHARACTER SET utf8 COLLATE utf8_unicode_ci DEFAULT NULL,
  `FatherMobilePhone` bigint(8) DEFAULT NULL,
  `MotherMobilePhone` bigint(8) DEFAULT NULL,
  `FatherProfession` varchar(30) COLLATE utf8_unicode_ci DEFAULT NULL,
  `MotherProfession` varchar(30) COLLATE utf8_unicode_ci DEFAULT NULL,
  `Observations` varchar(30) COLLATE utf8_unicode_ci DEFAULT NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci;

--
-- Dumping data for table `Student`
--

INSERT INTO `Student` (`ID`, `GradeId`, `StudentID`, `OrganizationId`, `FirstName`, `LastName`, `FatherFirstName`, `FatherLastName`, `DateOfBirth`, `PlaceOfBirth`, `Sex`, `Carnet`, `MobilePhone`, `Address`, `MotherFirstName`, `MotherLastName`, `FatherMobilePhone`, `MotherMobilePhone`, `FatherProfession`, `MotherProfession`, `Observations`) VALUES
(21, 'G_016', 'S_100000001', 116, 'Student', 'One', '', '', '', '', 'male', NULL, 8178109047, '', '', '', 0, 0, NULL, NULL, NULL),
(22, 'G_016', 'S_100000002', 116, 'Student', 'two', '', '', '', '', 'female', NULL, 0, '', '', '', 0, 0, NULL, NULL, NULL),
(23, 'G_002', 'S_100000003', 116, 'Student3', 'three', NULL, NULL, NULL, NULL, 'male', NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL);

-- --------------------------------------------------------

--
-- Table structure for table `Subject`
--

CREATE TABLE `Subject` (
  `ID` int(6) NOT NULL,
  `SubjectId` varchar(20) COLLATE utf8_unicode_ci NOT NULL,
  `Name` varchar(30) COLLATE utf8_unicode_ci DEFAULT NULL,
  `Abbreviation` varchar(30) COLLATE utf8_unicode_ci DEFAULT NULL,
  `GradeId` varchar(10) COLLATE utf8_unicode_ci NOT NULL,
  `OrganizationId` int(6) NOT NULL,
  `StaffId` varchar(30) COLLATE utf8_unicode_ci NOT NULL DEFAULT '0'
) ENGINE=InnoDB DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci;

--
-- Dumping data for table `Subject`
--

INSERT INTO `Subject` (`ID`, `SubjectId`, `Name`, `Abbreviation`, `GradeId`, `OrganizationId`, `StaffId`) VALUES
(12, 'SUB_0001', 'English 1A', 'Eng_1A', 'G_016', 116, 'E_100000030'),
(13, 'SUB_0002', 'English 1B', 'Eng_1B', 'G_002', 116, '0'),
(14, 'SUB_0003', 'Science 1A', 'Sci_1A', 'G_016', 116, 'E_100000030');

Consider handling issues of data display in application code — Strawberry, May 20 '20 at 19:14
What @Strawberry said. Doing pivots in SQL, especially in MySQL, is a notorious pain in the xxx neck. — O. Jones, May 20 '20 at 19:16
After examaning your data, your query is correct. Subjet2 has no Weightage bigger than 0, what result do oyu expect — nbk, May 20 '20 at 19:36
@nbk After increasing the weightage the value doesn't changes and I am sure how to do the calculation to get the cumulative marks on basis of weightage. — TRIKONINFOSYSTEMS, May 20 '20 at 19:59
your weightage selects the exams that are selected, in the example 3 5 and 6 and for them you get the marks. for every student. I don't understand what you want as result, so please show us that — nbk, May 20 '20 at 20:04
@nbk I updated the fiddle https://dbfiddle.uk/?rdbms=mysql_5.6&fiddle=a68a6145e61c5dd1a90d6d3431db0b66 with updated weightage, as you can see 'SUB_0001' has 4 exams, 3 of them are having Weightage. 'S_100000001' appeared 3 Exams with subjectid 'SUB_0001', out of which 2 Exams with ID 'EX_0002' and 'EX_0005' are having Weightage 10 and 80 so the Marks should be (10% of 77) + (80% of 80) = 71.7 But it is showing 80 only — TRIKONINFOSYSTEMS, May 20 '20 at 22:06

score 1 · Accepted Answer · edited Jun 20 '20 at 09:12

Ok with your last comment, your query would look like this

SET @sql = NULL;
SELECT
  GROUP_CONCAT(DISTINCT
               CONCAT('SUM(IF(sj.SubjectId = ''', SubjectId,''', ROUND((pa.`Marks` * p.`Weightage` / 100),1),0)) AS ',SubjectId)
              ) INTO @sql
FROM Subject;

SET @sql = CONCAT('SELECT s.ID, s.StudentID, s.FirstName, s.LastName, ', @sql, ' 
                  FROM Student s
                  JOIN Marks AS pa 
                  ON pa.StudentID = s.StudentID AND pa.OrganizationId = s.OrganizationId 
                  JOIN Exams p
                  ON p.ExamId = pa.ExamId AND p.OrganizationId = pa.OrganizationId
                  JOIN Subject sj
                  ON p.SubjectId = sj.SubjectId AND pa.OrganizationId = sj.OrganizationId
                  WHERE p.Weightage > 0
                 GROUP BY s.ID
                 ORDER BY s.ID');
#SELECT @sql;
PREPARE stmt FROM @sql;
EXECUTE stmt;



ID | StudentID   | FirstName | LastName | SUB_0001 | SUB_0002 | SUB_0003
-: | :---------- | :-------- | :------- | -------: | -------: | -------:
21 | S_100000001 | Student   | One      |     71.7 |      0.0 |      2.5
22 | S_100000002 | Student   | two      |     72.0 |      0.0 |      2.1
23 | S_100000003 | Student3  | three    |      0.0 |      1.2 |      1.5

db<>fiddle here

MySQL query to create a pivot table by joining 4 different table

1 Answers1

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