4 articles
This tag page groups all Schoolabe articles related to Database, so you can study one concept area without jumping between unrelated topics.
Start with the first article to build fundamentals, then move to deeper posts that cover implementation patterns, interview framing, common mistakes, and practical trade-offs.
Learn how to add a column in SQL using ALTER TABLE. Complete guide with examples for MySQL, PostgreSQL, SQL Server, and Oracle, including constraints and best practices.
Learn how to use SQL WHERE IS NOT NULL to filter out NULL values. Complete guide with examples, best practices, and common use cases.
Learn how to use SQL query descending order with ORDER BY DESC. Complete guide with examples, multiple columns, NULL handling, and best practices.
Learn what uniquely identifies each row in a table, including primary keys, unique constraints, and composite keys in database design.