CodeIgniter Migration for Admin Areas (India)

I have an ERP/School Management System built with PHP and CodeIgniter. The application stores address information using normalized relational database tables with foreign key relationships rather than free-text location fields. The countries table has already been populated with approximately 192 countries, so no country data is required. I need a CodeIgniter migration (preferred) or a MySQL SQL seed/insert script that populates the lower administrative levels for India. Existing Database Structure The following tables already exist: countries (already populated) states districts sub_districts These tables are linked using numeric IDs and foreign key relationships. Administrative Hierarchy The hierarchy should follow India's official administrative structure as closely as possible. India State District Sub-district (Tehsil, Taluk, Taluka, Mandal, Block, or the most appropriate official equivalent) The goal is to maintain a consistent four-level hierarchy used throughout the application. Application Flow The address selection process works as follows: User selects a Country. System loads the available States. User selects a State. System loads the corresponding Districts. User selects a District. System loads the available Sub-districts. User enters Address Line 1, Address Line 2, and any additional address details. Only the IDs of these administrative areas are stored within the database. Deliverables Please provide either: A CodeIgniter migration file (preferred) OR A MySQL SQL insert/seed script The deliverable should include: Complete list of Indian States Complete list of Districts Complete list of Sub-districts Correct parent-child relationships Proper foreign key mapping No duplicate records Clean, organized, and maintainable code Requirements Use official government or other well-maintained administrative datasets. Ensure the data is complete, accurate, and up to date. Parent-child relationships must be correctly mapped. The migration or SQL script should run without modification in a standard CodeIgniter project. Please Include in Your Proposal Estimated delivery time Your experience with PHP, CodeIgniter, and MySQL The administrative data source you intend to use Any assumptions made where administrative naming conventions may vary