HRM-System/docs/PLAN-data-migration.md

Data Migration Plan: Employee, Shift, and Attendance

Executive Summary

This document outlines a structured plan to import historical Employee, Shift, and Attendance records from the legacy data dump (rame_seb.sql) into the current HRM system. Based on user directives, we will replicate the legacy data as closely as possible to the new relational structure.

Architectural Approach & Data Mapping

1. Employee Details

• Source: Legacy users table.
• Target: Current users and employees tables.
• Approach:
  • We will read the legacy users rows.
  • For each row, create a User identity for authentication.
  • Password Rule: Explicitly set all imported users' passwords to 123456 (hashed using Laravel's Hash::make('123456')) to ensure smooth initial access.
  • Create the related Employee profile using the legacy HR details (phone, address, etc.), maintaining the mapping via user_id.

2. Shifts (The 48-Shift Strategy)

• Source: Legacy shifts table (contains ~48 half-hour interval shifts covering the 24-hour cycle, e.g., OPS 12:00AM-09:00AM).
• Target: Current shifts table.
• Approach:
  • Direct Replication: We will import all 48 distinct shift templates exactly as they are defined in the legacy system.
  • Scheduling: Since the legacy shifts are universally enabled for all 7 days (sunday through saturday = 1), we do not need complex roster logic. We will simply migrate the start_time, end_time, and is_night_shift logic into our new Shift templates, making them immediately available for assignment to Employees.

3. Attendance

• Source: Legacy attendances table.
• Target: Current attendance_records table.
• Approach:
  • Read the raw check_in_time, check_out_time, and working_hours from the legacy database.
  • Link them to the newly generated Employee ID rather than the old legacy User ID.
  • Map legacy attendance statuses (present, leave, etc.) to the new system's properties.
  • "Just Copy" strategy: Orphaned records (if any) will still be imported if the related user exists, preserving historical attendance integrity.

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Task Breakdown / Execution Plan

1. Database Preparation:
   • Load rame_seb.sql into a temporary secondary database connection in Laravel (e.g., legacy_db).
2. Shift Importer:
   • Write a Seeder/Command to insert the 48 shifts into the shifts table.
   • Retain legacy id mappings to properly link attendance records later.
3. Employee Importer:
   • Write a Command to stream legacy users.
   • Insert into users (password: 123456).
   • Insert into employees (associate with their legacy default shift_id).
4. Attendance Importer:
   • Write a Command to fetch all legacy attendances.
   • Remap IDs to the new structure and insert them sequentially into attendance_records.

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This plan is ready for execution. Run /create or confirm to proceed with writing the import scripts.