SQL queries, optimization, window functions
Master all subquery types with the research analogy. WHERE/FROM/SELECT subqueries, correlated subqueries with step-by-step row execution, EXISTS and NOT EXISTS, the same question solved five ways (JOIN, IN, EXISTS, derived table, CTE), performance comparison table, decision tree, subqueries in INSERT/UPDATE/DELETE, and five real-world patterns.
Master SQL aggregations with the post office analogy. GROUP BY rules, COUNT/SUM/AVG/MIN/MAX with NULL behavior, WHERE vs HAVING, CASE WHEN in SELECT/WHERE/ORDER BY/aggregations (pivot pattern), COALESCE, NULLIF, division by zero protection, aliases and scope, STRING_AGG, and conditional aggregation crosstab.
Master SQL from the execution order that makes everything click. Every WHERE clause with real examples: comparison operators, AND/OR/NOT with the precedence trap, BETWEEN, IN, NOT IN with the NULL trap, LIKE with wildcards, EXISTS and NOT EXISTS, IS NULL, ORDER BY, DISTINCT, TOP/LIMIT, and OFFSET pagination.
Master the differences between databases and data warehouses, OLTP vs OLAP, normalized vs star schema, row vs columnar storage. Plus detailed Dedicated vs Serverless SQL Pool comparison with cost calculations, decision framework, and real-world scenarios.
Master SCD Types 0, 1, 2, 3, and 6 with detailed table examples and real-life analogies. Covers implementation in Azure SQL, Synapse Data Flows, and Delta Lake MERGE. Includes edge cases, Medallion architecture integration, and interview questions.
Complete guide to Azure SQL Database for data engineers. Covers service tiers, DTU vs vCore, authentication methods, Managed Identity, firewall rules, stored procedures, temporal tables, pipeline integration, and cost optimization.
Azure SQL Database for Data Engineers: Setup, Configuration, and Pipeline Integration Read More »
Master SQL CTEs and subqueries. Learn when to use each, how to chain multiple CTEs, recursive CTEs for hierarchies, deduplication patterns, and real-world data engineering examples.
SQL CTEs and Subqueries Explained: When to Use Each and Why CTEs Win Read More »
Master every SQL join type with visual diagrams and real examples. Covers INNER, LEFT, RIGHT, FULL OUTER, CROSS, and SELF joins, plus ON vs WHERE, CTEs with joins, performance tips, and interview questions.
SQL Joins Explained: INNER, LEFT, RIGHT, FULL, CROSS, and SELF Joins with Real Examples Read More »
Master SQL window functions with real examples. Covers ROW_NUMBER, RANK, DENSE_RANK, NTILE, LAG, LEAD, running totals, moving averages, frame clauses, and the most common interview questions.
SQL Window Functions Explained: ROW_NUMBER, RANK, DENSE_RANK, LAG, LEAD, and More Read More »
