SQL and Databases
SQL and Databases15 lessons4 hr 41 min
A beginner course on relational databases and SQL. It starts with tables and keys, then reads data with SELECT, filtering, sorting, limiting, DISTINCT, aliases and NULL semantics.
Modules
Lessons open in reading order. Each one is a public page.
Databases and SELECT
3 lessonsLearn what a relational table is, how keys keep rows identifiable, and how SELECT, WHERE, ORDER BY, LIMIT, DISTINCT and NULL behave in the practice database.
Filtering and functions
3 lessonsBuild precise filters with boolean logic and LIKE, clean and transform values with string, date and number functions, and use aliases without tripping over evaluation order.
Aggregation and grouping
3 lessonsSummarize rows with COUNT, SUM, AVG, MIN and MAX, split them into buckets with GROUP BY, filter those buckets with HAVING, and handle NULLs and empty input correctly.
Joins and relationships
3 lessonsRecombine normalized tables with INNER, LEFT, RIGHT, CROSS and self joins, walk many-to-many relationships through a junction table, and compare result sets with UNION, INTERSECT and EXCEPT.
Subqueries, schema design and project
3 lessonsRead and write subqueries, CTEs, normalized schemas, indexes and transactions, then apply them in a capstone library database with its own schema and query set.