Learn to ask databases the right questions.
Read and reason through real SQL on a fictional bookshop database: SELECT, WHERE, AND/OR, IN, BETWEEN, LIKE, NULL, ORDER BY, LIMIT, aggregates, GROUP BY, HAVING and INSERT/UPDATE/DELETE, with every answer checked as you go.
Combine tables with every join type, filter with subqueries and EXISTS, structure queries with CTEs and CASE, and merge results with UNION, INTERSECT and EXCEPT, with every answer checked as you go.
Rank, compare and accumulate rows with window functions, walk hierarchies with recursive CTEs, and estimate index, scan and join costs like a query planner, with every answer checked as you go.
Build and query a fictional coffee roaster's MySQL database: data types, CREATE TABLE, primary and foreign keys, AUTO_INCREMENT, INSERT/UPDATE/DELETE, SELECT with LIMIT, CONCAT, IFNULL, DATE_FORMAT, GROUP BY and joins, with every answer checked as you go.
Join tables the MySQL way, wrap queries in views, write stored procedures, functions and triggers, keep data safe with transactions and design a clean schema, with every answer checked as you go.
Diagnose a slow MySQL 8 database like a professional: read slow logs and EXPLAIN, size B-trees and indexes, reason about locks, MVCC, partitions, replication lag, backups and server memory, with every answer checked as you go.
Work through real Oracle SQL on a fictional HR table: SELECT and DUAL, NULL handling with NVL, NVL2 and COALESCE, text, number and date functions, TO_CHAR and TO_DATE, CASE and DECODE, ROWNUM and FETCH FIRST and sequences, with every answer checked as you go.
Read and reason through real Oracle SQL on a fictional company schema: ANSI and (+) joins, subqueries, CONNECT BY hierarchies, recursive WITH, ROLLUP and CUBE, analytic functions and MERGE, with every answer checked as you go.
Calculate cardinalities and plan costs like the optimizer, use bind variables well, and write PL/SQL with cursors, exceptions, BULK COLLECT, FORALL, packages and Flashback, with every answer checked as you go.
Read and predict real T-SQL on a fictional bike shop database: SELECT TOP, OFFSET-FETCH, ISNULL, CAST and CONVERT, TRY_CAST, DATEADD and DATEDIFF, string functions, CASE, GROUP BY, HAVING, IDENTITY and INSERT, UPDATE, DELETE, with every answer checked as you go.
Work through real T-SQL for a fictional parts wholesaler: joins and their traps, variables, CASE, CTEs and recursion, IF and WHILE, stored procedures with OUTPUT parameters, transactions, TRY/CATCH, temp tables, the OUTPUT clause and MERGE, with every answer checked as you go.
Master window functions, APPLY and PIVOT, then go under the hood of SQL Server: clustered and nonclustered indexes, SARGable predicates, execution plans, statistics, parameter sniffing, isolation levels, locking and safe dynamic SQL, with every answer checked as you go.
Design and use a real desktop database for a fictional bike rental: tables, data types, primary keys, relationships, select and totals queries, criteria, forms, reports and imports, with every answer checked as you go.
Design related tables, enforce referential integrity and work out exactly what Access joins, totals, crosstab, parameter and action queries, macros and grouped reports produce, with every answer checked as you go.
Master the Access SQL dialect, IIf, Nz, crosstabs, action and parameter queries, normalisation to 3NF, data types, indexes, split front-end/back-end databases, linked tables, DAO recordsets and data quality on a fictional rental business, with every answer checked as you go.
Work through a fictional bike-rental database in PostgreSQL: psql, data types, identity columns, numeric, dates, :: casts, constraints, INSERT/UPDATE/DELETE, NULL, GROUP BY, generate_series and transactions, with every answer checked as you go.
Join and reshape data the PostgreSQL way with LATERAL, DISTINCT ON and recursive CTEs, query arrays and JSONB, rank and compare rows with window functions, and build views, materialized views and upserts, with every answer checked as you go.
Read EXPLAIN like the planner, size and choose B-tree, GIN and BRIN indexes, tune statistics, vacuum and memory, partition big tables and reason about MVCC, isolation and locks, with every answer checked as you go.
Learn to ask databases the right questions. The SQL track teaches the language itself: SELECT, filters, joins, subqueries, CTEs, window functions and query tuning. The MySQL, PostgreSQL, Oracle SQL, SQL Server T-SQL and Microsoft Access courses add what is different in each system: functions, data types, procedural code and administration.
Every lesson is a hands-on lab with the tables laid out in an interactive sheet. You work out exactly which rows and values a query returns, and the coach checks each answer instantly. That is how you learn to spot wrong joins and wrong totals before they reach a report. Each course ends with an exam and a certificate.
No. The tables are shown in the lab and you work out the query results there. You can run the same statements on your own server, and we recommend it.
Start with SQL Foundations, then choose the system your work uses: MySQL, PostgreSQL, Oracle, SQL Server or Access.
Yes. Each system course uses that system's own syntax and functions, for example TOP in T-SQL, ROWNUM and FETCH FIRST in Oracle, LIMIT in MySQL and PostgreSQL.
Pick a course, pay once and start right away. Your progress is saved in your account.
