SQL & Data

SQL queries, data warehouses, ETL and the modern data stack.

SQL & Data

SQL for Beginners: SELECT, WHERE and ORDER BY

Learn SQL from zero: how SELECT, WHERE and ORDER BY work, with a sample table, clear examples, common operators and beginner mistakes to avoid.

Read article →SQL & Data

SQL JOINs Explained with Simple Examples

SQL JOINs explained with two small tables: INNER, LEFT, RIGHT, FULL OUTER and CROSS JOIN, finding unmatched rows and avoiding duplicated totals.

Read article →SQL & Data

GROUP BY and Aggregate Functions in SQL

Learn SQL GROUP BY with SUM, COUNT, AVG, MIN and MAX: how NULLs affect results, WHERE vs HAVING, multi-column groups and pivot-style totals.

Read article →SQL & Data

SQL Window Functions: ROW_NUMBER, RANK and Running Totals

Learn SQL window functions with clear examples: ROW_NUMBER vs RANK vs DENSE_RANK, top N per group, running totals, moving averages and LAG/LEAD.

Read article →SQL & Data

CTEs and Subqueries in SQL

Learn when to use CTEs vs subqueries in SQL, with clear examples for filtering, ranking and recursive queries that make your BI reports easier to build.

Read article →SQL & Data

Connecting Power BI to SQL Databases

Step-by-step guide to connecting Power BI to SQL Server, PostgreSQL or MySQL: Import vs DirectQuery, native queries, query folding and gateways.

Read article →SQL & Data

Data Warehouse Basics: Facts, Dimensions and Grain

Learn data warehouse basics: fact tables, dimension tables, grain, surrogate keys and slowly changing dimensions, with SQL examples for BI beginners.

Read article →SQL & Data

ETL vs ELT: How Data Gets into Your Dashboards

ETL vs ELT explained simply: how each data pipeline works, pros and cons, popular tools, and how to choose the right approach for your BI reports.

Read article →SQL & Data

Snowflake vs BigQuery vs Databricks vs Fabric

Snowflake vs BigQuery vs Databricks vs Microsoft Fabric compared for BI: architecture, pricing models, Power BI fit, ease of use and which to pick.

Read article →SQL & Data

dbt for Analysts: Transform Data with SQL

Learn dbt as an analyst: build SQL models with ref(), add tests and docs, choose materializations and organize staging and marts, step by step.

Read article →SQL & Data

10 SQL Practice Projects for Your Portfolio

10 SQL practice projects for your data analyst portfolio, from beginner sales analysis to RFM segmentation, cohorts and query tuning, with datasets.

Read article →SQL & Data

PostgreSQL vs MySQL vs SQL Server for Analytics

PostgreSQL vs MySQL vs SQL Server for analytics: compare features, licensing, SQL dialects and Power BI fit, with the same query written in all three.

Read article →SQL & Data

Data Quality and Governance for BI Teams

A practical guide to data quality and governance for BI teams: six quality dimensions, SQL checks, roles, a metric glossary and a simple rollout plan.

Read article →SQL & Data

30 SQL Interview Questions for Data Analysts

30 SQL interview questions for data analysts with clear answers: joins, GROUP BY, NULLs, window functions, CTEs, plus classic coding problems solved.

Read article →