Notes — Module 01: Introduction to PostgreSQL¶

These are your personal study notes. Write freely and honestly. Incomplete notes are fine — they show where your understanding still needs work. Return to this file to add insights as they develop over time.

Module: [[modules/01_introduction]] Topic: [[postgresql]] Date started: Fill in when you start Status: Not started

Concept Map¶

Sketch how the concepts in this module relate to each other.

mindmap
  root((PostgreSQL Intro))
    Relational Model
      Relations / Tables
      Tuples / Rows
      Attributes / Columns
      Primary Keys
    psql Client
      Meta-commands
      SQL statements
      Database navigation
    Data Types
      TEXT vs VARCHAR
      TIMESTAMPTZ
      NUMERIC
      BOOLEAN
    CRUD Operations
      INSERT
      SELECT with WHERE
      UPDATE with WHERE
      DELETE with WHERE

Alternative: draw this on paper, photo it, and link the image here.

Key Insights¶

The "aha moments" — the things that, once understood, made the rest clear.

Fill in as you study
Fill in as you study

My Understanding¶

Explain the core concepts in your own words, as if teaching them to someone else.

The Relational Model¶

Your explanation here

What I'm still unsure about: Fill in

Why SQL is Declarative¶

Your explanation here

What I'm still unsure about: Fill in

NULL Behavior¶

Your explanation here

Connections to Other Topics¶

This module's concept	Connects to	How
SQL query language	[[django-fastapi-flask]]	Django ORM generates SQL; understanding it helps debug ORM behavior
Data types	[[async-python]]	asyncpg maps Postgres types to Python types
Schema design basics	[[systems-architecture]]	Database schema is part of overall system architecture

Questions That Arose¶

Log questions as they appear. Don't stop to answer them now — just capture them.

Add questions here as you study

Code Snippets Worth Remembering¶

Template for Creating a Table¶

CREATE TABLE entity_name (
    id          BIGSERIAL   PRIMARY KEY,
    name        TEXT        NOT NULL,
    created_at  TIMESTAMPTZ NOT NULL DEFAULT now(),
    updated_at  TIMESTAMPTZ NOT NULL DEFAULT now()
);

Why I'm saving this: good starting point for any new table

Safe Update / Delete Pattern¶

-- Always test with SELECT first using the same WHERE clause
SELECT * FROM table WHERE condition;
-- If the results look right, run the UPDATE or DELETE
UPDATE table SET column = value WHERE condition;

Why I'm saving this: prevents accidental full-table updates

What Tripped Me Up¶

Mistakes I made, misconceptions I had, things that confused me more than they should have.

Fill in as you study

Summary in My Own Words¶

Write a 3–5 sentence summary of this entire module without looking at any notes.

Fill in after completing the module.

Last updated: Fill in date