Learning SQL, 2nd edition (Alan Beaulieu) (Z-Library)

【One-Line Pitch】 A practical, example-driven introduction to SQL that takes you from creating your first database to writing complex queries with joins, subqueries, and set operations—ideal for application developers, analysts, and anyone who needs to interact with relational data. 【Book Arc】 - **Opening (~0%–15%)**: Introduces the relational model, SQL statement classes, and the nonprocedural nature of the language, then walks you through creating and populating a MySQL database—covering data types, table design, and basic INSERT/UPDATE/DELETE statements. - **Early (~15%–40%)**: Dives into the query primer: the SELECT clause, FROM and WHERE clauses, grouping, and sorting. Then moves to filtering techniques (equality, range, membership, pattern matching) and handling NULL values. - **Middle (~40%–70%)**: Explains multi-table queries with inner joins, self-joins, and non-equi-joins, then introduces set operations (UNION, INTERSECT, EXCEPT) with practical rules for compound query results. - **Late (~70%–90%)**: Covers data generation, conversion, and manipulation—working with strings, numbers, and temporal data, plus conversion functions and time zone handling. - **Ending (~90%–100%)**: Focuses on grouping and aggregate functions: implicit versus explicit groups, counting distinct values, handling NULLs, and single-column, multicolumn, and expression-based grouping. 【Key Takeaways】 - **SQL is nonprocedural** (Early): you declare what data you want, not how to get it—the database engine figures out the execution plan. This mental shift is essential for writing effective queries. - **Table design precedes querying** (Early): the book walks through a three-step process—design, refinement, and building schema statements—showing that good queries start with well-structured tables and appropriate data types. - **The WHERE clause is your primary filter** (Early): equality, range (BETWEEN), membership (IN), and pattern matching (LIKE) conditions let you narrow results precisely; understanding NULL behavior is critical since NULL comparisons require IS NULL, not =. - **Joins connect data across tables** (Middle): inner joins, self-joins, and non-equi-joins are explained with the ANSI join syntax, emphasizing that join conditions and filter conditions serve different purposes. - **Set operations treat query results as sets** (Middle): UNION, INTERSECT, and EXCEPT combine result sets with rules about column counts and data types; set operation precedence matters when chaining multiple operations. - **Built-in functions transform data** (Late): string manipulation, arithmetic functions, and temporal data handling (including time zones) let you convert and shape data directly in queries rather than in application code. - **Grouping enables aggregation** (Ending): aggregate functions like COUNT, SUM, and AVG work with GROUP BY to summarize data; understanding implicit versus explicit groups and how NULLs are handled prevents common mistakes. 【Reading Tips】 - **Skim Chapter 1** if you already know basic database concepts; the real value starts with Chapter 2's hands-on database creation. - **Deep-read Chapters 3–5** (Query Primer, Filtering, Querying Multiple Tables)—these are the core of SQL and appear in almost every real-world query you'll write. - **Practice the exercises** at the end of each chapter; the book is designed for hands-on learning, and the exercises reinforce the annotated examples. - **Pay special attention to NULL handling** (Chapter 4) and join conditions (Chapter 5)—these are the most common sources of bugs for beginners. - **Use the book as a reference** for the data generation and manipulation chapter (Chapter 7); you don't need to memorize every function, just know what's available. 【Coverage Limits】 The excerpts cover roughly the first half of the book (through Chapter 8 on grouping and aggregates). Later chapters on subqueries, advanced joins, and indexing are not covered in this guide.