Beginners - Simplify Database

SQL for data analysis roadmap in 9 stages: basics, summarize, clean, statistics, window functions, funnels and cohorts, data models, performance, tools around SQL

SQL for Data Analysis: A Step-by-Step Roadmap

Simplify Database / October 26, 2026

What to learn, in what order, to use SQL for real data analysis: 9 stages with free tutorials, an 8-week study plan and a first portfolio project.

SQL self join: the Employees table joined to itself, matching each ManagerID to the manager's EmployeeID

SQL

SQL SELF JOIN Explained Simply (With Employee and Manager Examples)

Simplify Database / October 22, 2026

What a SQL self join is and how to write one: show each employee with their manager, keep the top of the hierarchy with LEFT JOIN, compare related rows, find pairs and duplicates, and build a full org chart with a recursive CTE.

Delphi

Delphi Basics: Variables, Data Types, If, Case and Loops Explained Simply

Simplify Database / October 19, 2026

Learn Object Pascal basics in Delphi: variables, constants, data types, strings, if/else, case and for, while and repeat loops, with runnable examples.

25 SQL interview questions by topic, and the logical order SQL runs a query: FROM, WHERE, GROUP BY, HAVING, SELECT, ORDER BY

SQL

25 SQL Interview Questions for Beginners (With Answers)

Simplify Database / October 19, 2026

25 SQL interview questions that come up again and again for junior roles, with short answers you can say out loud: joins, GROUP BY, NULL, keys, indexes, ACID, and three classic write-a-query tasks.

Delphi

What Is Delphi? Install Delphi Community Edition and Build Your First App

Simplify Database / October 16, 2026

A beginner’s guide to Delphi: what it is, what it’s used for, how to install the free Community Edition, and how to build your first Windows app step by step.

SQL DISTINCT turns 8 department rows into 3, and a column alias renames Salary * 12 to AnnualSalary

SQL

SQL DISTINCT and Column Aliases Explained Simply

Simplify Database / October 14, 2026

How SQL DISTINCT removes duplicate rows (and why it applies to every selected column), how it treats NULL, COUNT(DISTINCT), and how to use column and table aliases, including why an alias works in ORDER BY but not in WHERE.

SQL LIKE, IN and BETWEEN cheat sheet with wildcard examples

SQL

SQL LIKE, IN and BETWEEN Explained Simply

Simplify Database / October 12, 2026

Search text with LIKE, match a list with IN and filter ranges with BETWEEN, with simple examples, the NOT IN NULL trap and the date BETWEEN mistake that hides rows.