SQL for Analytics: From Queries to Window Functions

SQL for Analytics: From Queries to Window Functions is simply a system way of 14 lessons that build a complete, interview-ready knowing of the topic. Work done them successful order, past usage the quiz and flashcards successful each instruction to revise.

What this people covers

• Relational Databases, Keys & Reading an Entity Relationship Diagram - Tables, superior and overseas keys, relationships, and reference a schema sketch fast.
• Normalisation & Denormalisation: What Each One Costs You - The normal forms successful plain terms, and why analytics deliberately denormalises.
• Query Execution Order and Why It Explains Most Errors - Why the database runs FROM earlier SELECT, and which beginner errors that explains.
• Filtering Precisely: SELECT, WHERE, IN, LIKE & BETWEEN - Getting precisely the rows you meant, including the operators that softly driblet rows.
• Aggregation & Grouping, Including HAVING versus WHERE - Aggregates, grouping sets, and the HAVING-versus-WHERE mobility interviewers ask.
• Joins successful Depth: Inner, Left, Full, Cross & Self Joins - Every subordinate type pinch a worked row-level illustration of what it returns.
• Join Fan-Out & Duplicate Rows: The Silent Wrong Answer - How a one-to-many subordinate inflates totals, and really to observe it earlier you report.
• Handling Nulls Correctly - Why null breaks comparisons, aggregates and joins, and the functions that tame it.
• Subqueries, Common Table Expressions & Readable SQL - Restructuring nested logic into readable steps a reviewer tin follow.
• Window Functions: Ranking, Running Totals, Lag & Lead - The functions that determine beardown SQL rounds, each pinch a business usage case.
• Date, Time & Cohort Queries That Interviews Reuse - Month-on-month change, rolling windows and first-purchase cohorts successful SQL.
• Query Performance: Indexes, Scans & Writing Efficient SQL - Why a query is slow, really to publication a plan, and the rewrites that really help.
• Ten SQL Patterns That Cover Most Interview Questions - Ten reusable query shapes, from second-highest worth to gap-and-island problems.
• Case Study: Answering a Business Question End to End successful SQL - One vague petition turned into a validated query and a written answer.