JOINs - Simplify Database

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

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.

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.

Venn diagrams showing INNER, LEFT, RIGHT and FULL JOIN results

Database, SQL

SQL JOINs Explained Simply — Connecting Tables for Beginners

Simplify Database / May 19, 2026

If you’ve started learning SQL, you’ve probably hit the same wall every beginner hits: JOINs. They look complicated. The diagrams