# Database Column Error Fix Summary

## Issue Description
The application was throwing a database error:
```
ডেটাবেইস কুয়েরি ত্রুটি: SQLSTATE[42S22]: Column not found: 1054 Unknown column 'fp.received_by' in 'on clause'
```

## Root Cause Analysis
The issue occurred because the code was trying to join the `users` table using a column `fp.received_by` that doesn't exist in the `fee_payments` table. The actual column name in the database is `created_by`.

## Files Fixed

### 1. Primary File: `fees/income_report.php`
- **Issue**: Line 36 had `LEFT JOIN users u ON fp.received_by = u.id`
- **Fix**: Changed to `LEFT JOIN users u ON fp.created_by = u.id`

### 2. Debug Files
- `comprehensive_debug.php` - Fixed the same JOIN clause issue
- `debug_income_report.php` - Fixed the same JOIN clause issue  
- `fees/diagnose_income_report.php` - Fixed the same JOIN clause issue
- `fees/income_report_backup.php` - Fixed the same JOIN clause issue

### 3. Data Population Script
- `fees/populate_sample_data.php`
  - Fixed array keys from `'collected_by'` to `'created_by'`
  - Fixed INSERT statement column names from `collected_by` to `created_by`
  - Fixed execute parameter from `$payment['collected_by']` to `$payment['created_by']`

## Verification
Created test script `test_fix.php` to verify the fix works correctly.

## Impact
All income report functionality should now work properly without database errors. The JOIN operations will correctly link fee payments to the users who created them.

## Note
This appears to be a naming inconsistency in the codebase where some parts used `received_by`/`collected_by` while the actual database schema uses `created_by`. All references have been standardized to use the correct column name.