Category: SQL
You are here if you have a table and a question, and another export into a sheet is how the answer gets worse. These articles are the SQL series in category form. The numbered tutorials start with a playground and the core commands, then reading rows, filtering, sorting, grouping, and joins. Later tutorials cover subqueries, changing rows, views and indexes, and making a query faster and easier to keep. One extra primer, outside that numbered run, asks what SQL is and why you would learn it.
Do not start in the middle because a title mentions joins. Joins make sense after you can read and filter a single table. The series hub states the order. The category page is only the shelf.
Where to start: open the SQL series. Use the first part on that page. If you only needed the word, the primer is enough. If you need to write the query on Monday, use the playground and go in order.
SQL Tutorial 8: Modifying Data with SQL
Change data safely with INSERT, UPDATE, and DELETE on the customers and orders toy schema. Practice row adds, targeted edits, and careful deletes, plus a light take on…
SQL Tutorial 7: Subqueries in SQL
Subqueries nest one query inside another so you can filter and shape results with answers from other answers. Learn scalar, IN, EXISTS, and derived tables on the customers…
SQL Tutorial 6: Joins in SQL
Connect customers to orders with INNER and LEFT joins, using keys on purpose. Learn how join grain can explode row counts, when not to join, and how to…
SQL Tutorial 5: Aggregate Functions and Grouping Data
Turn rows into summaries with COUNT, SUM, AVG, MIN, and MAX. Group with GROUP BY, and learn when HAVING filters groups while WHERE filters rows, so your totals…
SQL Tutorial 4: Filtering and Sorting Data in SQL
Filter rows with WHERE, combine conditions with AND and OR, and use IN, BETWEEN, and careful LIKE patterns. Sort with ORDER BY and learn NULL basics so your…
