SQL Basics: A Beginner's Guide to DDL, DML, Filtering, and CASE WHEN

A new tutorial on DEV Community walks beginners through the foundational concepts of SQL using a school database as a practical example. The guide covers Data Definition Language (DDL) commands such as CREATE TABLE and ALTER TABLE, which are used to structure a database before any data is entered. It then explains Data Manipulation Language (DML) operations — INSERT, UPDATE, and DELETE — for populating and maintaining records, highlighting the importance of using WHERE clauses to avoid unintended bulk changes. The article also details filtering techniques using operators like BETWEEN, IN, LIKE, and logical connectors AND and OR to retrieve precise data with SELECT queries. The tutorial aims to help learners understand not just SQL syntax but the reasoning behind each concept, making it a practical starting point for those new to database management.