SQL
Frag deine Daten, was du willst.
SQL is the language of databases. Every post, like and game score in an app like Nova lives in database tables, and SQL is how you ask those tables questions. This track starts from zero: reading tables with SELECT, filtering and sorting, counting and grouping, joining tables, changing data safely, designing your own tables, and finally subqueries, CTEs and window functions.
Every lesson works with the same small dataset from Nova, a made-up social app (users, posts, likes and scores) and shows the exact result of every query, so you always know what answer to expect.
- Lektionen
- 25
- Zeit
- 3 Std.
- Level
- Einsteiger
Die Lektionen dieses Kurses gibt es vorerst nur auf Englisch.
- Bronze offen
- Silber offen
- Gold gesperrt
Bereit, es zu beweisen?
Drei Prüfungen warten auf dich: Bronze, Silber und Gold.
Das wirst du können
- Read and filter any table with SELECT and WHERE
- Summarize data with COUNT, SUM, AVG, GROUP BY and HAVING
- Combine tables with INNER JOIN and LEFT JOIN
- Insert, update and delete rows safely inside transactions
- Design tables with keys, constraints and indexes
- Build a leaderboard with subqueries, CTEs and window functions
Die Reise
1 Modul 1Databases and tables
What a relational database is, how tables are built, and your first SELECT.
0 / 32 Modul 2Filtering and sorting
Keep only the rows you want, handle NULL correctly and put results in order.
0 / 43 Modul 3Aggregation
Turn many rows into answers: counts, totals, averages and groups.
0 / 34 Modul 4Joins
Combine tables: match rows, keep the unmatched ones and find what is missing.
0 / 35 Modul 5Changing data
Add, change and remove rows, and use transactions so mistakes can be undone.
0 / 46 Modul 6Designing tables
Create tables with the right types, protect them with constraints and speed them up with indexes.
0 / 47 Modul 7Powerful queries
Subqueries, EXISTS, CTEs, CASE and window functions for real leaderboards.
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