Calculation is only calculating one row and not all rows (PHP)

PHP
1

I have a slight calculation probelm.

Below is the my output:

Student: Mayur Patel (u0867587)
Course: INFO101 - Bsc Information Communication Technology Course Mark:62

Module: CHI2550 - Modern Database Applications Module Mark: 41 Mark Percentage: 68 Grade: B

Session Session Mark Session Weight
AAB 72 20%
Session Session Mark Session Weight
AAE 67 40%

Module: CHI2513 - Systems Strategy Module Mark: 31 Mark Percentage: 62 Grade: B

Session Session Mark Session Weight
AAD 61 50%

There is only one problem with this output. The only last little probelm is that the Course Mark is incorrect. It should add up to 65 (adding the mark percentage together (68 + 63 = 130) and divide by number of modules (2) and that should equal 65). Instead it adds up to 62. Now the calculations I have done is 200% correct. The problem those is that the the reason it is outputting 62 is because it is only selecting the rows for the last module (so calculation it is doing is 62 divide by 1 which equals 62). Now the reason for this is because my foreach loop where the course details and calculation is in only outputs one course detail from the database (as there is no need to show the course details multiple times). Because of this the calculation is only picking out rows from the last row only.

What I want to know is that is there a way the calculation can go through all the rows but I can keep it in the same foreach loop which displays only once course detail. If calculation is not in same foreach loop then I will get undefined variables.

Thank You

Below is the code I believe is relevant for this question. The foreach is for the course details only.

 $output = "";  
        
        $studentId = false;
        
        // load query data in a multidimensional array 
        $dataArray = array(); 
        
        while ($row = mysql_fetch_array($result)) { 
            $dataArray[$row['CourseId']]['CourseName'] = $row['CourseName']; 
            $dataArray[$row['CourseId']]['ModuleId'] = $row['ModuleId']; 
            $dataArray[$row['CourseId']]['SessionWeight'] = $row['SessionWeight']; 
            $dataArray[$row['CourseId']]['Mark'] = $row['Mark']; 
            $dataArray[$row['CourseId']]['Modules'][$row['ModuleId']]['ModuleName'] = $row['ModuleName']; 
            $dataArray[$row['CourseId']]['Modules'][$row['ModuleId']]['Sessions'][$row['SessionId']]['Mark'] = $row['Mark']; 
            $dataArray[$row['CourseId']]['Modules'][$row['ModuleId']]['Sessions'][$row['SessionId']]['SessionWeight'] = $row['SessionWeight']; 
            
                 if($studentId != $row['StudentUsername']) 
    { 

        //Student has changed 
        $studentId = $row['StudentUsername']; 

        $output .= "<strong>Student:</strong> {$row['StudentForename']} {$row['StudentSurname']} ({$row['StudentUsername']})\
"; 

    } 
        } 

        // just for debugging purposes, let's do a print_r of the array 
        // eliminate this line when you don't need it anymore 
        // print_r($dataArray); 

        foreach ($dataArray as $courseId => $courseData) {  
           // elaborate course data 
           
           $markTotal = 0;  
             $markGrade = 0;  
             $weightSession = 0; 
             $moduleCount = 0;
             $courseTotal = 0;
             
              $markTotal += round($courseData['Mark'] / 100 * $courseData['SessionWeight']);  
                $weightSession  += ($courseData['SessionWeight']);  
                $markGrade += round($markTotal /  $weightSession * 100); 
                $moduleCount += count($courseData['ModuleId']);
                 $courseTotal += ($markGrade / $moduleCount);
            
                 echo $output;  
       
       }  // <-- end of courses foreach
2

I see you messed up the array I gave you in your other post :slight_smile:

These lines:


            $dataArray[$row['CourseId']]['ModuleId'] = $row['ModuleId']; 
            $dataArray[$row['CourseId']]['SessionWeight'] = $row['SessionWeight']; 
            $dataArray[$row['CourseId']]['Mark'] = $row['Mark'];

Will only contain the data for the last module of the course, and the last session of the last module of the course.

Further, there are some errors in your calculations (it looks like you deleted a lot of code in your post, so I just added some semi-coded loops to clarify the position all calculations should be in):


        foreach ($dataArray as $courseId => $courseData) {  

           // elaborate course data 
           $moduleCount = 0;
           $courseTotal = 0;
           $courseGrade = 0;

           foreach () {   // I guess you left out part of the code ... here should the module loop be

             $markTotal = 0;  
             $markGrade = 0;  
             $weightSession = 0;

             foreach () {   //  ... here should the session loop be

               $markTotal += round($courseData['Mark'] / 100 * $courseData['SessionWeight']);  
               $weightSession  += $courseData['SessionWeight'];  

             }

             $markGrade += round($markTotal /  $weightSession * 100); 

             // To count the modules, simply add 1 to the counter
             $moduleCount++;
             // Add the mark grade to the course total
             $courseTotal += $markGrade;
           }  

           // at the end of each course, you can calculate the course grade
           $courseGrade = $courseTotal / $moduleCount;
       }  // <-- end of courses foreach

       echo $output;
3

Hi,

I didn’t delete the code, what I did was that I capied and paste the calculation again and put it in the foreach loop for the course but that ends up doing the calculation for the last row only. Anyway I scrapped that and went with the way you have done it. The calculation has worked well but there is just one last question and then this page is completley finished. The only problem is that to be able to get the answer of the calculation, I had to display the course details at the bottom, so the output looks like this below:

Student: Mayur Patel (u0867587)
Module: CHI2550 - Modern Database Applications Module Mark: 41 Mark Percentage: 68 Grade: B

Session Session Mark Session Weight
AAB 72 20%
Session Session Mark Session Weight
AAE 67 40%

Module: CHI2513 - Systems Strategy Module Mark: 31 Mark Percentage: 62 Grade: B

Session Session Mark Session Weight
AAD 61 50%

Course: INFO101 - Bsc Information Communication Technology Course Mark: 65

I want the course details to be outputted above the modules so it looks like this below:

Student: Mayur Patel (u0867587)
Course: INFO101 - Bsc Information Communication Technology Course Mark: 65

Module: CHI2550 - Modern Database Applications Module Mark: 41 Mark Percentage: 68 Grade: B

Session Session Mark Session Weight
AAB 72 20%
Session Session Mark Session Weight
AAE 67 40%

Module: CHI2513 - Systems Strategy Module Mark: 31 Mark Percentage: 62 Grade: B

Session Session Mark Session Weight
AAD 61 50%

Problem is that if I keep the course details at the bottom then the calculation works. I move it to the top and then the calculation would not work as the calculation for the $courseGrade is at the bottom and so for the Course Mark it will display 0.

So my question is how can I move the course details to the top and still have the answer of the calculation displayed for the course mark?

Below is the code:


$dataArray = array(); 
        
        while ($row = mysql_fetch_array($result)) { 
            $dataArray[$row['CourseId']]['CourseName'] = $row['CourseName']; 
            $dataArray[$row['CourseId']]['Modules'][$row['ModuleId']]['ModuleName'] = $row['ModuleName']; 
            $dataArray[$row['CourseId']]['Modules'][$row['ModuleId']]['Sessions'][$row['SessionId']]['Mark'] = $row['Mark']; 
            $dataArray[$row['CourseId']]['Modules'][$row['ModuleId']]['Sessions'][$row['SessionId']]['SessionWeight'] = $row['SessionWeight']; 
            
                 if($studentId != $row['StudentUsername']) 
    { 

        //Student has changed 
        $studentId = $row['StudentUsername']; 

        $output .= "<strong>Student:</strong> {$row['StudentForename']} {$row['StudentSurname']} ({$row['StudentUsername']})\
"; 

    } 
        } 

        // just for debugging purposes, let's do a print_r of the array 
        // eliminate this line when you don't need it anymore 
        // print_r($dataArray); 

        foreach ($dataArray as $courseId => $courseData) {  
           // elaborate course data 
           
           // elaborate course data 
           $moduleCount = 0;
           $courseTotal = 0;
           $courseGrade = 0;
           
           $courseHTML = ""; 
           
           $courseHTML .= "<br><table><tr><th>Course:</th><td>" . $courseId .  " - "  . $courseData['CourseName'] . "</td>"; 

           foreach ($courseData['Modules'] as $moduleId => $moduleData) { 
             // elaborate module data 
             $moduleHTML = "";
             
             $moduleHTML .= "<br><table><tr><th>Module:</th><td>" . $moduleId . " - " . $moduleData['ModuleName'] ."</td>"; 

             $markTotal = 0;  
             $markGrade = 0;  
             $weightSession = 0; 
             $grade = "";  
             $sessionsHTML = ""; 
             
              
             foreach ($moduleData['Sessions'] as $sessionId => $sessionData) { 
                // elaborate session data 
                $markTotal += round($sessionData['Mark'] / 100 * $sessionData['SessionWeight']);  
                $weightSession  += ($sessionData['SessionWeight']);  
                $sessionsHTML .= "<table><tr><th>Session</th><th>Session Mark</th><th>Session Weight</th></tr><tr><td>" . $sessionId . "</td><td>" . $sessionData['Mark'] . "</td><td>" . $sessionData['SessionWeight'] ."%</td></tr></table>\
";  
             } 
             $markGrade = round($markTotal /  $weightSession * 100); 
             
              // To count the modules, simply add 1 to the counter
             $moduleCount++;
             // Add the mark grade to the course total
             $courseTotal += $markGrade;

              
             if ($markGrade >= 70) { $grade = "A"; }  
             else if ($markGrade >= 60 && $markGrade <= 69) { $grade = "B"; }  
             else if ($markGrade >= 50 && $markGrade <= 59) { $grade = "C"; }  
             else if ($markGrade >= 40 && $markGrade <= 49) { $grade = "D"; }  
             else if ($markGrade >= 30 && $markGrade <= 39) { $grade = "E"; }  
             else if ($markGrade >= 0 && $markGrade <= 29) { $grade = "F"; }              

             $moduleHTML .= " <th>Module Mark:</th><td>" . $markTotal . "</td><th>Mark Percentage:</th><td>" . $markGrade . "</td><th>Grade:</th><td>" . $grade . " </td></tr></table><br>";   
             $output .= $moduleHTML . $sessionsHTML; 
           }  // <-- end of sessions foreach 
         }  // <-- end of modules foreach 
         
         // at the end of each course, you can calculate the course grade
           $courseGrade = ($courseTotal / $moduleCount);
           
         $courseHTML .= " <th>Course Mark:" . $courseGrade . "</th></tr></table>";
                    
           $output .= $courseHTML;
          //Display the output  
       echo $output;  
       
       }  // <-- end of courses foreach
4

Put the output for the course details in another variable, for example $courseOutput.
Once you have the course output complete (that is including the course grade), just add it to the output like this:

$output = $courseOutput . $output;