# Fix Summary: Jessore Board Bangla Grading in Transposed Tabulation Sheet

## Problem Identified
The transposed tabulation sheet was incorrectly calculating Bangla grades for student 20250020 in class 10 due to two issues:

1. **Duplicate Results Issue**: Multiple results existed for the same student-subject combination in the database, causing the system to potentially average or incorrectly process multiple results for the same subject.

2. **Incorrect Grading Logic**: The `getCombinedBanglaResult` function was using percentage-based grading instead of the specific Jessore Board rules for Bangla subjects.

## Root Cause
- Database contained multiple result entries for the same student and subject (e.g., multiple entries for "Bangla 2nd Paper")
- The query `SELECT r.*, s.student_id as roll_number FROM results r JOIN students s ON r.student_id = s.id WHERE s.class_id = ? AND r.session = ? AND r.exam_type = ?` was retrieving ALL results without deduplication
- The `getLanguageSubjectGrade` function was using average percentage instead of the specific Jessore Board rule (CQ average > 22 AND MCQ average > 9)

## Solution Implemented

### 1. Fixed Duplicate Results Query
**File**: `reports/transposed_tabulation_sheet.php` (lines ~126-136)
**Change**: Modified the results query to only get the latest result for each student-subject combination:

```sql
-- Before
SELECT r.*, s.student_id as roll_number
FROM results r
JOIN students s ON r.student_id = s.id
WHERE s.class_id = ? AND r.session = ? AND r.exam_type = ?

-- After  
SELECT r.*, s.student_id as roll_number
FROM results r
JOIN students s ON r.student_id = s.id
WHERE s.class_id = ? AND r.session = ? AND r.exam_type = ?
AND r.id IN (
    SELECT MAX(id)
    FROM results
    WHERE student_id = r.student_id AND subject_id = r.subject_id AND session = ? AND exam_type = ?
    GROUP BY student_id, subject_id
)
```

### 2. Applied Correct Jessore Board Bangla Rules
**File**: `reports/transposed_tabulation_sheet.php` (lines ~413-421)
**Change**: Modified the `getCombinedBanglaResult` function to use the correct Jessore Board grading rules:

```php
// Before
$combined['grade'] = getLanguageSubjectGrade($combined['cq_marks'], $combined['mcq_marks'], $cq_full_marks, $mcq_full_marks);

// After
// For Bangla subjects: determine pass/fail based on Jessore Board rules
// CQ average > 22 AND MCQ average > 9 to pass
if ($combined['cq_marks'] > 22 && $combined['mcq_marks'] > 9) {
    // Calculate overall percentage for grade assignment
    $overall_marks = $combined['cq_marks'] + $combined['mcq_marks'];
    $total_possible_marks = 100; // Assuming 50+50 for CQ+MCQ
    $percentage = ($overall_marks / $total_possible_marks) * 100;
    
    if ($percentage >= 80) $combined['grade'] = 'A+';
    elseif ($percentage >= 70) $combined['grade'] = 'A';
    elseif ($percentage >= 60) $combined['grade'] = 'A-';
    elseif ($percentage >= 50) $combined['grade'] = 'B';
    elseif ($percentage >= 40) $combined['grade'] = 'C';
    elseif ($percentage >= 33) $combined['grade'] = 'D';
    else $combined['grade'] = 'F';
} else {
    // Student fails according to Jessore Board Bangla rules
    $combined['grade'] = 'F';
}
```

## Verification
- The system now correctly handles duplicate results by only using the latest result for each student-subject combination
- Bangla grading now follows Jessore Board rules: CQ average > 22 AND MCQ average > 9 to pass
- The fix prevents incorrect grade calculations that were occurring due to averaging multiple results for the same subject

## Impact
- Student grades are now calculated accurately according to Jessore Board standards
- Eliminates grade calculation errors caused by duplicate entries in the database
- Maintains data integrity by using only the most recent result for each subject