SQL Course for Beginners

Lesson 1 • Setting Up a Practice Environment

Guides students through installing or accessing a SQL environment for hands-on practice. Removes technical barriers so all exercises in later chapters can be completed immediately.

Lesson 2 • Understanding Database Schema

Explains schema as the blueprint defining tables, columns, and data types. Students can read an entity-relationship diagram and map it to actual database objects.

Lesson 3 • What Is a Relational Database

Defines relational databases, tables, rows, and columns as core structures. Establishes the conceptual model students will apply throughout all subsequent SQL work.

Lesson 1 • Filtering NULL Values

Addresses NULL as the absence of a value and its unique filtering behaviour. Students avoid common NULL-related logic errors in WHERE clauses.

Lesson 2 • Basic SELECT Syntax

Covers the minimal SELECT…FROM structure and column selection. Students write their first working queries and understand query execution order.

Lesson 3 • Sorting and Limiting Results

Introduces ORDER BY and row-limiting clauses to control output presentation. Students deliver results in meaningful order and restrict large result sets efficiently.

Lesson 4 • Working with Column Expressions

Shows how to compute new values and rename columns within SELECT. Students enrich query output without modifying stored data.

Lesson 1 • Date and Time Functions

Teaches extraction, arithmetic, and formatting of date and time values. Students answer time-based business questions such as age, duration, and period filtering.

Lesson 2 • String Functions

Covers functions that manipulate character data such as trimming, casing, and substring extraction. Students clean and reformat text columns directly in query output.

Lesson 3 • Conditional Logic with CASE

Introduces the CASE expression for inline conditional branching within SELECT. Students categorise and label data without requiring application-layer logic.

Lesson 4 • Numeric Functions

Introduces rounding, absolute value, modulo, and power functions for numeric columns. Students perform precise calculations required in financial and analytical queries.

Lesson 1 • Filtering Groups with HAVING

Distinguishes HAVING from WHERE and shows how to filter aggregated results. Students apply post-aggregation conditions to isolate meaningful summary groups.

Lesson 2 • Aggregate Functions

Introduces COUNT, SUM, AVG, MIN, and MAX as tools for computing summary statistics. Students understand how aggregates collapse multiple rows into single result values.

Lesson 3 • Rollup and Grouping Sets

Introduces ROLLUP, CUBE, and GROUPING SETS for multi-level subtotals. Students build hierarchical summary reports without writing multiple separate queries.

Lesson 1 • Outer Joins

Covers LEFT, RIGHT, and FULL OUTER JOIN to include unmatched rows. Students retrieve complete datasets even when related records are absent.

Lesson 2 • Subqueries in Join Context

Shows how derived tables and subqueries can act as join sources. Students compose modular queries that pre-filter or pre-aggregate data before joining.

Lesson 3 • Joining More Than Two Tables

Extends JOIN logic to chains of three or more tables. Students navigate complex schemas and produce multi-entity result sets accurately.

Lesson 4 • Inner Join Fundamentals

Explains how INNER JOIN returns only matching rows from both tables. Students link related tables using primary and foreign key relationships.

Lesson 1 • Transactions and Rollback

Introduces ACID properties and manual transaction control with COMMIT and ROLLBACK. Students protect data integrity by wrapping multi-step changes in explicit transactions.

Lesson 2 • Deleting Rows

Explains DELETE and TRUNCATE with their behavioural and performance differences. Students remove data safely and understand when each command is appropriate.

Lesson 3 • MERGE for Upsert Operations

Covers the MERGE statement for combining insert and update logic in one pass. Students synchronise target tables with source data efficiently and atomically.

Lesson 4 • Inserting Rows

Covers single-row and multi-row INSERT syntax including column-list best practices. Students populate tables correctly whilst respecting constraints and default values.

Lesson 1 • Constraints and Data Integrity

Explains PRIMARY KEY, FOREIGN KEY, UNIQUE, CHECK, and NOT NULL constraints. Students enforce business rules at the database level to prevent invalid data entry.

Lesson 2 • Creating and Using Views

Introduces views as stored SELECT queries that simplify access and enforce security. Students create, query, and update views to abstract complex logic from end users.

Lesson 3 • Sequences and Auto-Generated Keys

Covers SEQUENCE objects and identity columns for generating surrogate keys. Students implement reliable, conflict-free key generation strategies in multi-user environments.

Lesson 4 • Indexes for Query Performance

Explains how indexes accelerate data retrieval and the trade-offs they introduce. Students create targeted indexes and understand when indexes help or hurt performance.

Lesson 1 • Pivoting and Unpivoting Data

Shows how to rotate rows into columns and columns into rows for reporting. Students reshape data to match the format required by dashboards and downstream tools.

Lesson 2 • Query Optimisation Fundamentals

Introduces execution plans, SARGability, and common anti-patterns that degrade performance. Students diagnose slow queries and apply targeted rewrites to improve efficiency.

Lesson 3 • Set Operations

Teaches UNION, INTERSECT, and EXCEPT for combining or comparing result sets. Students merge data from multiple queries while controlling duplicate handling.

Lesson 4 • Window Functions

Covers OVER, PARTITION BY, and ORDER BY within window function syntax. Students compute running totals, rankings, and moving averages without collapsing rows.