Create DB struct functions

[BaronSwango]

Desired Behavior

Create various functions for each table struct to execute queries and retrieve data. Link IDs to objects through foreign keys already created in the schema. Functions include updating a row, deleting a row, retrieving a row/multiple rows, and retrieving linked rows through foreign keys in a specified table struct.

User Story

As a developer, I want easy access to all data stored in all tables of the relational database, so I will create separate, clear, and effective functions to perform queries and retrievals of data.