Tag: SQL
SQL and Data Science Interview Questions: A Practical Guide to Practice and Preparation
Practice for SQL and data science interviews with six real-world questions — three easy, two medium, and one hard — all built on one downloadable dataset, with step-by-step answers, common traps, and tips for explaining your thinking.
PostgreSQL for Beginners: A Step-by-Step Guide to Database Management
Learn PostgreSQL step by step: install it, connect with psql, create a database and tables, manage users and permissions, and back up and restore your data.
SQLAlchemy: A Complete Guide to Python Database Management
Learn SQLAlchemy 2.0 from scratch: connect to a database, define models, create, read, update, and delete records, work with relationships and joins, avoid the N+1 query problem, manage transactions, and handle schema changes with Alembic.
Cleaning Messy Data with Pure SQL: A Beginner's Guide
Learn how to clean messy data with pure SQL, from trimming whitespace to fixing duplicates, with no extra tools needed.
Database Security and Privacy: A Beginner's Guide to Protecting Sensitive Data
Learn how to secure a database and protect sensitive data: access control, encryption (and which data to encrypt), SQL injection defense, backups, auditing, and a practical checklist.
SQL Window Functions: Running Totals & Rankings
Learn SQL window functions for running totals, rankings, and moving averages, with clear beginner examples.
Mastering SQL Subqueries: A Beginner-to-Advanced Guide
A guide to SQL subqueries: syntax, types, and real examples for cleaner, faster queries.
MySQL with Docker: A Beginner’s Guide to Running Databases in Containers
Run MySQL in Docker: pull the official image, persist data with volumes, set environment variables, and connect from a client or app — a step-by-step beginner's guide.
Why Your SQL Query Is Slow (And How to Fix It)
Wondering why your SQL query is slow? Learn the most common causes — missing indexes, SELECT *, bad WHERE clauses — and how to fix them.
Database Design: A Beginner's Guide to Planning It Right
Learn database design step by step — requirements, entities, relationships, and normalization — built for beginner web designers.
SQL JOINs Explained: A Beginner's Guide
Learn SQL JOINs with clear examples: INNER, LEFT, RIGHT, and FULL JOIN explained for absolute beginners.
SQL Injection: How It Works and How to Prevent It
Learn what SQL injection is, how attackers exploit it, and how to prevent it with parameterized queries and input validation.
What Is a Data Analyst? A Beginner's Guide to Roles, Skills, and Tools
Learn what a data analyst does, how the role compares to data scientists and data engineers, the skills and tools you need (SQL, spreadsheets, Power BI, Python), and a step-by-step path to becoming one.
The Role of Databases and Dashboards in Today's Business
Discover the role of databases and dashboards in modern business, from raw data storage to visual, decision-ready reporting.