Detective's Journal

DDL vs DML: Understanding SQL Command Types (With Visual Examples)

Learn the difference between DDL and DML in SQL. Visual guide covering CREATE, ALTER, DROP vs SELECT, INSERT, UPDATE, DELETE with examples and quiz.

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Primary Key vs Foreign Key: The Complete Visual Guide (2026)

February 19, 2026

11 min read

Hristo Bogoev

Primary Key vs Foreign Key: The Complete Visual Guide (2026)

Learn the difference between primary key and foreign key in SQL with visual diagrams, code examples, and practical detective-themed scenarios.

SQL vs Excel: When to Use Each (With Side-by-Side Examples)

SQL vs Excel: which should you learn? Visual comparison with side-by-side code examples, decision flowchart, and practical use cases for every role.

SQL Window Functions Explained: The Complete Visual Guide (2026)

Master SQL window functions with visual examples. Learn ROW_NUMBER, RANK, LAG, LEAD, and more with before/after diagrams and interactive quizzes.

DELETE vs TRUNCATE in SQL: When to Use Each (Visual Guide)

Learn the key differences between DELETE and TRUNCATE in SQL with visual examples, decision flowcharts, and common mistakes to avoid.

SQL UNION vs UNION ALL: When to Use Each (With Visual Examples)

Learn the key differences between UNION and UNION ALL in SQL. Visual examples showing when duplicates matter, performance tips, and a decision flowchart.

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