How to improve/maximize current Database/Table Structure efficiency? - mysql

Question

The current structure of my Database tables are as follows; I have two tables, Users, and Skills, with the following columns:
Users
user_id f_name l_name biography password email role
_____________________________________________________________________
1 John Program Short Bio Password johnprogram# Programmer
2 Jeff Analyst Another Bio Password jeffanalyst# Finance Analyst
3 Mister Manager My Bio Password mrmanager# Project Manager
Skills
user_id skill_1 skill_1_details skill_2 skill_2_details skill_3 skill_3_details
_________________________________________________________________________________
1 PHP John writes PHP Python John writes Python Perl John writes Perl
2 Excel I use Excel daily SAP SAP Reporting Reporting Reports created with Excel
3 Billing Oversee Bill. Team Workflow Assignment I assign team acc.
Whenever I am querying the data in the tables to display on a Profile Page, the info is displayed as follows:
Name: John Program
Role: Programmer
Short Bio
Skill: PHP
Details: John writes PHP
Skill: Python
Details: John writes Python
Skill: Perl
Details: John writes Perl
Questions:
1) What re-adjustments/changes should be made to the table structures to increase efficiency/flexibility given the display requirements?
2) If I were to add a "Previous Projects Using Skill" column, for efficiency, would I add it to the second table as follows?:
user_id skill_1 skill_1_details projects_using_skill_1
_________________________________________________________________________________
1 PHP John writes PHP 8 Python John writes Python Perl John writes Perl
2 Excel I use Excel daily 12 SAP SAP Reporting Reporting Reports created with Excel
3 Billing Oversee Bill. Team 3 Workflow Assignment I assign team acc.

Answer 1

For the skill - user relation, you can have two different solutions: if each user has its own skills and details, than you can use a skill table to represent them, with only one skill per user per row (so if a user has four skills, the table will have four rows):
Skills (user_id, skill, detail)
with primary key the couple user_id, skill.
In this way, to find all the skills for a certain user, you can join the two table and find all the relevant information.
If instead several users can have the same skills, you should use three tables:
Users (user_id, f_name, ...)
Skills (skill_id, skill_name, skill_detail)
UsersSkills (user_id, skill_id)
or, if you want that each user has its own details about a skill, but you want to share the skills, you could do something like the following:
Users (user_id, f_name, ...)
Skills (skill_id, skill_name)
UsersSkills (user_id, skill_id, skill_detail)
For your second question, if a user has done several projects using a certain skill, assuming that you have selected the first solution above, you can define a new table:
ProjectUsers (user_id, skill, project_id)
with primary key all the three attributes, and with user_id, skill foreign key for the Skills table.