I don't believe OP is aware of the existence of table joins, and just reproduced what he thought was mentioned.

Meanwhile, the DB operation he described is clearly a table join (create a new table by creating a relationship between two existing tables).

That is also quite clearly a good reason for a prospective employer to lose interest in OP as a potential recruiter, and why his projects on Github fail to impress anyone. Portfolio projects only work in favor of a job applicant if they are any good, but if they are all a bunch of crap that is poorly put together and showcases incompetence, such as setting up a database system that tries to reinvent the wheel to fill in the gap of not knowing the very basics, then obviously that is disheartening to any potential recruiter.