Description
Coding
SQL & Databases
Learn to query and organize data with 32 practical SQL lessons, from your first SELECT to joins, transactions, and analytical reports.
Connect tables, validate data, use transactions, and build reports.
- 1
Joining related tables
Connect records through primary and foreign keys.
18 min
- 2
Keeping unmatched rows
Use LEFT JOIN to retain members with no matching activity.
18 min
- 3
Joining several tables
Follow a relationship chain without multiplying unrelated rows.
18 min
- 4
Filtering grouped results
Separate row filters from aggregate filters.
18 min
- 5
Subqueries
Use a query result inside another query.
18 min
- 6
Existence checks
Ask whether a related row exists without duplicating outer rows.
18 min
- 7
CASE and missing-value fallbacks
Build conditional result values without changing stored data.
18 min
- 8
Keys and constraints
Enforce required values, unique identifiers, and valid relationships.
18 min
- 9
Transactions and rollback
Group changes and undo a transaction when it should not be kept.
18 min
- 10
Project: a member activity report
Combine joins, aggregates, and fallbacks into a complete report.
18 min