Convert json to sql data

I have 3 types of JSON files which have different structures (they have little differences). All of these files have nested objects. That's why I am unable to use freely available JSON-to-CSV converter to upload this content to my PostgreSQL database I need to do this conversion to create test data for my project. You can write a simple PHP file.. no framework needed! Steps to do 1. A form which allows me to upload JSON file & also select the JSON objects type (3 types should be supported) (Depending upon the selected type, you know how the JSON object structure will look like) 2. Upload the given objects into PostgreSQL table (Make unique check before). Each object has a unique id. Insert a JSON object to SQL table only when it doesn't exist. 3. Empty cells should be set to NULL in db 4. Date value should be saved with timezone 5. No data should be lost! Note: all the 3 formats will use the same table to insert data.