CS50x 2026 - Lecture 7 - SQL | CS50

This CS50 lecture introduces Structured Query Language (SQL) and its declarative programming paradigm, contrasting it with procedural languages like C and Python. The lecture uses real-world data collected via a Google Form to demonstrate SQL's capabilities, including downloading data in CSV format and using Python to analyze it. It covers fundamental SQL operations (CRUD: Create, Read, Update, Delete), data types, and key concepts like primary and foreign keys. The lecture further explores relationships within data using examples from the IMDB database, including one-to-one, one-to-many, and many-to-many relationships. It also addresses SQL injection attacks and race conditions, emphasizing the importance of sanitizing user input and using database transactions to ensure data integrity. The lecture concludes with a discussion of indexing for query optimization.

Outlines

Part 1: Introduction, Data Collection

Part 2: Data Analysis with Python

Part 3: SQL Basics, CRUD Operations

Part 4: Database Design, Relationships

Part 5: Optimization, Integration

Part 6: Security, Data Integrity

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CS50x 2026 - Lecture 7 - SQL

CS50

Part 1: Introduction, Data Collection

Introduction to SQL: A Declarative Language for Data Manipulation

Gathering and Preparing Data: From Google Forms to Flat File Databases

Part 2: Data Analysis with Python

Analyzing Data with Python: Reading and Iterating Through CSV Files

Counting Language Preferences: From Variables to Dictionaries in Python

Part 3: SQL Basics, CRUD Operations

Transitioning to Relational Databases: Introducing SQL and SQLite

Selecting and Transforming Data: Basic SQL Queries and Functions

Data Manipulation: Inserting, Deleting, and Updating Data in SQL

Part 4: Database Design, Relationships

Modeling Data Relationships: From Spreadsheets to Relational Databases

Exploring the IMDB Database: Schemas, Data Types, and Relationships

Joining Tables and Nested Queries: Retrieving Related Data in SQL

Many-to-Many Relationships: Linking Shows and People Through the Stars Table

Part 5: Optimization, Integration

Optimizing Queries: Creating Indexes for Faster Data Retrieval

Combining Python and SQL: Using the CS50 Library for Data Analysis

Part 6: Security, Data Integrity

SQL Injection Attacks: Understanding and Preventing Security Vulnerabilities

Race Conditions and Data Integrity: Ensuring Accurate Updates in Concurrent Environments

CS50x 2026 - Lecture 7 - SQL

CS50

Part 1: Introduction, Data Collection

00:43Introduction to SQL: A Declarative Language for Data Manipulation

Introduction to SQL: A Declarative Language for Data Manipulation

02:18Gathering and Preparing Data: From Google Forms to Flat File Databases

Gathering and Preparing Data: From Google Forms to Flat File Databases

Part 2: Data Analysis with Python

06:30Analyzing Data with Python: Reading and Iterating Through CSV Files

Analyzing Data with Python: Reading and Iterating Through CSV Files

13:44Counting Language Preferences: From Variables to Dictionaries in Python

Counting Language Preferences: From Variables to Dictionaries in Python

Part 3: SQL Basics, CRUD Operations

23:42Transitioning to Relational Databases: Introducing SQL and SQLite

Transitioning to Relational Databases: Introducing SQL and SQLite

32:14Selecting and Transforming Data: Basic SQL Queries and Functions

Selecting and Transforming Data: Basic SQL Queries and Functions

45:52Data Manipulation: Inserting, Deleting, and Updating Data in SQL

Data Manipulation: Inserting, Deleting, and Updating Data in SQL

Part 4: Database Design, Relationships

52:27Modeling Data Relationships: From Spreadsheets to Relational Databases

Modeling Data Relationships: From Spreadsheets to Relational Databases

1:00:56Exploring the IMDB Database: Schemas, Data Types, and Relationships

Exploring the IMDB Database: Schemas, Data Types, and Relationships

1:11:13Joining Tables and Nested Queries: Retrieving Related Data in SQL

Joining Tables and Nested Queries: Retrieving Related Data in SQL

1:27:30Many-to-Many Relationships: Linking Shows and People Through the Stars Table

Many-to-Many Relationships: Linking Shows and People Through the Stars Table

Part 5: Optimization, Integration

1:39:21Optimizing Queries: Creating Indexes for Faster Data Retrieval

Optimizing Queries: Creating Indexes for Faster Data Retrieval

1:45:50Combining Python and SQL: Using the CS50 Library for Data Analysis

Combining Python and SQL: Using the CS50 Library for Data Analysis

Part 6: Security, Data Integrity

1:53:04SQL Injection Attacks: Understanding and Preventing Security Vulnerabilities

SQL Injection Attacks: Understanding and Preventing Security Vulnerabilities

2:07:09Race Conditions and Data Integrity: Ensuring Accurate Updates in Concurrent Environments

Race Conditions and Data Integrity: Ensuring Accurate Updates in Concurrent Environments