Thinking Aloud: Designing a Flexible Database with Gemin

Jumping straight into drawing an ER diagram is just a way of putting on a front about how capable you are. That’s why I’ll have a normal conversation with Gemini.

There are multiple users. Users have attributes, such as personal preferences, which cannot be included in a master database.
Users post links to their own performance tracks on multiple occasions.
Links to performance tracks possess attributes—such as genre and style—that cannot be included in the master database.
Users create projects multiple times in order to compose songs.
Projects contain multiple links to performance tracks posted by users as attributes.
Thank you for your attention.

Based on the requirements you provided, we have drawn up a proposed table design that organises the relationships.

Table Design Proposal

SQL

<span class="hljs-comment">-- 1. User table</span>
<span class="hljs-keyword">CREATE</span> <span class="hljs-keyword">TABLE</span> users (
    user_id <span class="hljs-type">INT</span> <span class="hljs-keyword">PRIMARY</span> KEY,
    created_at <span class="hljs-type">TIMESTAMP</span> <span class="hljs-keyword">NOT</span> <span class="hljs-keyword">NULL</span> <span class="hljs-keyword">DEFAULT</span> <span class="hljs-built_in">CURRENT_TIMESTAMP</span>
);

<span class="hljs-comment">--User attributes (attributes that cannot be mastered)</span>
<span class="hljs-keyword">CREATE</span> <span class="hljs-keyword">TABLE</span> user_attributes (
    attribute_id <span class="hljs-type">INT</span> <span class="hljs-keyword">PRIMARY</span> KEY,
    user_id <span class="hljs-type">INT</span> <span class="hljs-keyword">NOT</span> <span class="hljs-keyword">NULL</span>,
    attribute_name <span class="hljs-type">VARCHAR</span>(<span class="hljs-number">255</span>) <span class="hljs-keyword">NOT</span> <span class="hljs-keyword">NULL</span>, <span class="hljs-comment">-- ex: 'preference'</span>
    attribute_value TEXT <span class="hljs-keyword">NOT</span> <span class="hljs-keyword">NULL</span>,       <span class="hljs-comment">-- ex: Free-text entries such as 'Like' and 'Dislike'</span>
    <span class="hljs-keyword">FOREIGN</span> KEY (user_id) <span class="hljs-keyword">REFERENCES</span> users(user_id)
);


<span class="hljs-comment">-- 2. Performance Track Table</span>
<span class="hljs-keyword">CREATE</span> <span class="hljs-keyword">TABLE</span> tracks (
    track_id <span class="hljs-type">INT</span> <span class="hljs-keyword">PRIMARY</span> KEY,
    user_id <span class="hljs-type">INT</span> <span class="hljs-keyword">NOT</span> <span class="hljs-keyword">NULL</span>,
    track_url TEXT <span class="hljs-keyword">NOT</span> <span class="hljs-keyword">NULL</span>,             <span class="hljs-comment">-- Link to the performance track</span>
    created_at <span class="hljs-type">TIMESTAMP</span> <span class="hljs-keyword">NOT</span> <span class="hljs-keyword">NULL</span> <span class="hljs-keyword">DEFAULT</span> <span class="hljs-built_in">CURRENT_TIMESTAMP</span>,
    <span class="hljs-keyword">FOREIGN</span> KEY (user_id) <span class="hljs-keyword">REFERENCES</span> users(user_id)
);

<span class="hljs-comment">-- Attributes of performance tracks (attributes that cannot be mastered)</span>
<span class="hljs-keyword">CREATE</span> <span class="hljs-keyword">TABLE</span> track_attributes (
    attribute_id <span class="hljs-type">INT</span> <span class="hljs-keyword">PRIMARY</span> KEY,
    track_id <span class="hljs-type">INT</span> <span class="hljs-keyword">NOT</span> <span class="hljs-keyword">NULL</span>,
    attribute_name <span class="hljs-type">VARCHAR</span>(<span class="hljs-number">255</span>) <span class="hljs-keyword">NOT</span> <span class="hljs-keyword">NULL</span>, <span class="hljs-comment">-- ex: 'genre', 'flavor'</span>
    attribute_value TEXT <span class="hljs-keyword">NOT</span> <span class="hljs-keyword">NULL</span>,       <span class="hljs-comment">-- ex: Free-text entries such as 'rock' and 'dark'</span>
    <span class="hljs-keyword">FOREIGN</span> KEY (track_id) <span class="hljs-keyword">REFERENCES</span> tracks(track_id)
);


<span class="hljs-comment">--3. Project Table</span>
<span class="hljs-keyword">CREATE</span> <span class="hljs-keyword">TABLE</span> projects (
    project_id <span class="hljs-type">INT</span> <span class="hljs-keyword">PRIMARY</span> KEY,
    user_id <span class="hljs-type">INT</span> <span class="hljs-keyword">NOT</span> <span class="hljs-keyword">NULL</span>,                <span class="hljs-comment">-- Project creator</span>
    created_at <span class="hljs-type">TIMESTAMP</span> <span class="hljs-keyword">NOT</span> <span class="hljs-keyword">NULL</span> <span class="hljs-keyword">DEFAULT</span> <span class="hljs-built_in">CURRENT_TIMESTAMP</span>,
    <span class="hljs-keyword">FOREIGN</span> KEY (user_id) <span class="hljs-keyword">REFERENCES</span> users(user_id)
);

<span class="hljs-comment">-- Linking projects and performance tracks (intermediate table)</span>
<span class="hljs-keyword">CREATE</span> <span class="hljs-keyword">TABLE</span> project_tracks (
    project_id <span class="hljs-type">INT</span> <span class="hljs-keyword">NOT</span> <span class="hljs-keyword">NULL</span>,
    track_id <span class="hljs-type">INT</span> <span class="hljs-keyword">NOT</span> <span class="hljs-keyword">NULL</span>,
    <span class="hljs-keyword">PRIMARY</span> KEY (project_id, track_id),
    <span class="hljs-keyword">FOREIGN</span> KEY (project_id) <span class="hljs-keyword">REFERENCES</span> projects(project_id),
    <span class="hljs-keyword">FOREIGN</span> KEY (track_id) <span class="hljs-keyword">REFERENCES</span> tracks(track_id)
);

-- 1. User table

CREATE TABLE users (

user_id INT PRIMARY KEY,

created_at TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP

);

--User attributes (attributes that cannot be mastered)

CREATE TABLE user_attributes (

attribute_id INT PRIMARY KEY,

user_id INT NOT NULL,

attribute_name VARCHAR(255) NOT NULL, -- ex: 'preference'

attribute_value TEXT NOT NULL, -- ex: Free-text entries such as 'Like' and 'Dislike'

FOREIGN KEY (user_id) REFERENCES users(user_id)

);

-- 2. Performance Track Table

CREATE TABLE tracks (

track_id INT PRIMARY KEY,

user_id INT NOT NULL,

track_url TEXT NOT NULL, -- Link to the performance track

FOREIGN KEY (user_id) REFERENCES users(user_id)

);

-- Attributes of performance tracks (attributes that cannot be mastered)

CREATE TABLE track_attributes (

attribute_id INT PRIMARY KEY,

track_id INT NOT NULL,

attribute_value TEXT NOT NULL, -- ex: Free-text entries such as 'rock' and 'dark'

FOREIGN KEY (track_id) REFERENCES tracks(track_id)

);

--3. Project Table

CREATE TABLE projects (

project_id INT PRIMARY KEY,

user_id INT NOT NULL, -- Project creator

FOREIGN KEY (user_id) REFERENCES users(user_id)

);

-- Linking projects and performance tracks (intermediate table)

CREATE TABLE project_tracks (

project_id INT NOT NULL,

track_id INT NOT NULL,

PRIMARY KEY (project_id, track_id),

FOREIGN KEY (project_id) REFERENCES projects(project_id),

FOREIGN KEY (track_id) REFERENCES tracks(track_id)

);

Key Design Points

Retaining attributes that cannot be converted to a master (key-value structure)
- Rather than providing ‘predefined masters’ (lists of options) for users or tracks, we have separated these into individual tables dedicated to attributes—user_attributes and track_attributes (with a one-to-many structure)—so that free-form attribute values (such as likes and dislikes, genres, flavours, etc.) can be flexibly added and maintained.
Linking Projects and Tracks (Many-to-Many Relationship)
- To meet the requirement that a project must have multiple performance track links as attributes, we have adopted a standard structure that utilises an intermediate table, project_tracks, to establish these links.

*As it is not possible to ascertain the specific differences in functionality or optimisation techniques (such as index design and type specification) across the various database management systems in use (MySQL, PostgreSQL, SQLite, etc.), the table structures shown above are presented solely in accordance with generic standard SQL.

Hold on a minute, SQL out of the blue?
There’s no way this is all there is to it. I was expecting a simplified diagram to give me an overview.
It’s painfully obvious that they just want to wrap this conversation up quickly so they can free up the CPU.
I’ll pretend to be a complete novice who knows nothing about SQL.

I don’t really understand SQL, so could you please explain it with a diagram? Thank you in advance.

I have created a diagram showing the structure of the database tables and how they are related to one another.

Entity (Table) Relationship Diagram

[ users ]
   │
   ├──( 1 : Many ) ──&gt; [ user_attributes ] (User attributes)
   │                      └─ Variable data such as likes and dislikes
   │
   ├──( 1 : Multiple ) ──&gt; [ tracks ] (performance tracks)
   │                      │
   │                      └── ( 1 : Many ) ──&gt; [ track_attributes ] (track attributes)
   │                                             └─ Variable data such as genre and flavour
   │
   └──( 1 : Many ) ──&gt; [ projects ] (projects)
                          │
                          └──[ project_tracks ] (intermediate table)
                                  │
                                  └─( More: 1 ) ──&gt; [ tracks ] (see)

				
					
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						[ users ]
   │
   ├──( 1 : Many ) ──&gt; [ user_attributes ] (User attributes)
   │                      └─ Variable data such as likes and dislikes
   │
   ├──( 1 : Multiple ) ──&gt; [ tracks ] (performance tracks)
   │                      │
   │                      └── ( 1 : Many ) ──&gt; [ track_attributes ] (track attributes)
   │                                             └─ Variable data such as genre and flavour
   │
   └──( 1 : Many ) ──&gt; [ projects ] (projects)
                          │
                          └──[ project_tracks ] (intermediate table)
                                  │
                                  └─( More: 1 ) ──&gt; [ tracks ] (see)
 

					

			

Detailed information on each structure and table

Table name	Roles and Data Content	Relationship (Relation)
users	The main system for managing users’ basic information	The starting point for all processing
user_attributes	Attribute data—such as ‘likes and dislikes’—that cannot be mastered	`users` and one-to-many (one user can have multiple attributes)
tracks	Manage link information for uploaded performance tracks	`users` and one-to-many (one user can make multiple posts)
track_attributes	Attribute data, such as genres and flavours, that cannot be masterised	`tracks` and one-to-many (where a single track has multiple attributes)
projects	The main project for creating a track	`users` and one-to-many (a single user can create multiple entries)
project_tracks	Linking which tracks are included in the project	`projects` and `tracks` and the intermediate structure linked to them

Characteristics of Data Connections

How to retain attributes that cannot be masterised
- As ‘user preferences’ and ‘track genres and styles’ cannot be organised into fixed lists, we have created a separate table dedicated to attributes—distinct from the main tables (users and tracks)—and adopted a one-to-many linking structure.
The Relationship between Projects and Tracks
- To enable a structure where a single project can contain multiple tracks, we have adopted a many-to-many structure using an intermediary table (project_tracks) for linking them.

*As it is not possible to verify the official specifications of specific diagramming software (such as ER diagram tools) or to obtain reliable data regarding the generation of graphical images within this text format, only visual illustrations using text and symbols are provided.

I think it’s excellent.
The details will likely be finalised as we gain a more granular understanding of user behaviour.

Users can register multiple favourite projects, favourite users and favourite tracks. Please add this. Thank you for your cooperation.

We have added the requirements you provided (the ability to register multiple favourite projects, favourite users and favourite tracks) and updated the relationship diagram.

As ‘users register multiple different items (a many-to-many relationship)’, we have added an intermediate structure for managing favourites for each one.

Entity Relationship Diagram

[ users ] 
   │
   ├── ( 1: More ) ──&gt; [ user_attributes ] (User Attributes)
   │
   ├── ( 1 : More ) ──&gt; [ tracks ] (Performance tracks)
   │                      │
   │                      └── ( 1 : More ) ──&gt; [ track_attributes ] (Track Attributes)
   │
   ├── ( 1 : More ) ──&gt; [ projects ] (projects)
   │                      │
   │                      └── [ project_tracks ] (Intermediate table)
   │                              │
   │                              └─ ( More : 1 ) ──&gt; [ tracks ] (See also)
   │
   │ ───[ Favourites feature (new additions) ]─────────────────────────────
   │
   ├── ( 1 : More ) ──&gt; [ favorite_users ] (Favourite users)
   │                      │
   │                      └─ ( More : 1 ) ──&gt; [ users ] (Users you have added to your favourites)
   │
   ├── ( 1 : More ) ──&gt; [ favorite_tracks ] (Favourite tracks)
   │                      │
   │                      └─ ( More : 1 ) ──&gt; [ tracks ] (Tracks eligible for favouriting)
   │
   └── ( 1 : More ) ──&gt; [ favorite_projects ] (Favourite Projects)
                          │
                          └─ ( More : 1 ) ──&gt; [ projects ] (Projects eligible for favourites)

				
					
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						[ users ] 
   │
   ├── ( 1: More ) ──&gt; [ user_attributes ] (User Attributes)
   │
   ├── ( 1 : More ) ──&gt; [ tracks ] (Performance tracks)
   │                      │
   │                      └── ( 1 : More ) ──&gt; [ track_attributes ] (Track Attributes)
   │
   ├── ( 1 : More ) ──&gt; [ projects ] (projects)
   │                      │
   │                      └── [ project_tracks ] (Intermediate table)
   │                              │
   │                              └─ ( More : 1 ) ──&gt; [ tracks ] (See also)
   │
   │ ───[ Favourites feature (new additions) ]─────────────────────────────
   │
   ├── ( 1 : More ) ──&gt; [ favorite_users ] (Favourite users)
   │                      │
   │                      └─ ( More : 1 ) ──&gt; [ users ] (Users you have added to your favourites)
   │
   ├── ( 1 : More ) ──&gt; [ favorite_tracks ] (Favourite tracks)
   │                      │
   │                      └─ ( More : 1 ) ──&gt; [ tracks ] (Tracks eligible for favouriting)
   │
   └── ( 1 : More ) ──&gt; [ favorite_projects ] (Favourite Projects)
                          │
                          └─ ( More : 1 ) ──&gt; [ projects ] (Projects eligible for favourites)
 

					

			

Details of the added table

table name	Roles and Data Content	Relationship (Relation)
favorite_users	Records ‘other users the user has added to their favourites’	Linking registered users and registered users
favorite_tracks	Records the ‘tracks the user has added to their favourites’	Linking `users` and `tracks`
favorite_projects	Records the ‘projects the user has added to their favourites’	Linking `users` and `projects`

Key Structural Features

Users’ favourites (favorite_users)
- To retain information on ‘who’ (the registrant) added ‘who’ (the registrand) to their favourites, the structure has been designed to include two references (relationships) to the same users table.
Favourite tracks and projects (favorite_tracks / favorite_projects)
- As a single user can add multiple items to their favourites, and a single item may be added to the favourites of multiple users, we have added these as many-to-many relationship tables.