· 3 min read

Learn SQL in German: Abfragen, Joins & Aggregatfunktionen in 74 Flashcards

Learn SQL with German backs: WHERE vs HAVING, joins, COUNT, subqueries and constraints in 74 flashcards, plus fixes for TRUNCATE, clause order and NOT IN.

Database cylinder with table grid and join circles among floating flashcards

Studying. But it's also a video game. 🎮

Flashcards, quizzes and games that make you actually remember.

Start playing — it's free

Posted by

Deck OM9054 — SQL: Abfragen, Joins & Aggregatfunktionen is the German edition of our English SQL deck, with the same 74 cards. The fronts stay in English, because that is how the keywords are written (SELECT, HAVING, LEFT JOIN), and the backs explain them in German. Each review links a keyword to its German term: Unterabfrage, Ergebnismenge, Fremdschlüssel. This is the vocabulary you will see in German documentation, job interviews and IHK exams.

Study this deck: SQL: Abfragen, Joins & Aggregatfunktionen

1 / 10
Question

SQL

Knew itLearning

Tap the card for the answer · swipe right if you knew it, left if not

Sample cards

FrontBack (German)
WHERE vs HAVINGWHERE filtert Zeilen vor der Gruppierung; HAVING filtert Gruppen nach der Aggregation
COUNT(*) vs COUNT(column)COUNT(*) zählt alle Zeilen; COUNT(column) zählt die Nicht-NULL-Werte
Why can't you use = NULL?Jeder Vergleich mit NULL ergibt NULL (weder wahr noch falsch)
LEFT JOIN vs LEFT OUTER JOINSie sind identisch – OUTER ist optional
Correlated subqueryVerweist auf Spalten der äußeren Abfrage (einmal pro Zeile ausgeführt)
UNION vs UNION ALLUNION entfernt Duplikate; UNION ALL behält alle Zeilen (schneller)
UNIQUE vs PRIMARY KEYMehrere UNIQUE-Constraints, aber nur ein PRIMARY KEY
VARCHAR vs CHARVariable vs feste Länge (mit Leerzeichen aufgefüllt)

What the 74 cards cover

DQL/DDL/DML/DCL, SELECT, DISTINCT, LIMIT/TOP, LIKE with % and _, IN, BETWEEN (einschließlich), IS NULL, ORDER BY ASC/DESC, INNER/LEFT/RIGHT/FULL/CROSS joins and self-joins, COUNT, SUM, AVG, MIN, MAX, GROUP BY, HAVING, scalar and correlated subqueries, EXISTS, UNION, aliases, INSERT, UPDATE, DELETE, TRUNCATE, primary and foreign keys (Primär-/Fremdschlüssel), normalization, CREATE/ALTER/DROP TABLE, data types, and the NOT NULL, UNIQUE and DEFAULT constraints.

Three backs to correct

  • Card 61 (DELETE vs TRUNCATE): "TRUNCATE kann nicht rückgängig gemacht werden" depends on the database. In PostgreSQL and SQL Server, a TRUNCATE inside a transaction can be rolled back. In MySQL and Oracle it commits automatically. Add „DBMS-abhängig" to the back.
  • Card 40 (Order of SQL clauses): this is the order you write the clauses in. The database runs them in a different order: FROM → WHERE → GROUP BY → HAVING → SELECT → ORDER BY → LIMIT. Add a second card for that order. It also explains card 39 (no aggregates in WHERE) and why a column alias works in ORDER BY but not in WHERE.
  • Card 46 (IN vs EXISTS): "EXISTS ist oft schneller" is outdated, because modern query optimizers usually turn both into the same plan. The difference that matters is NOT IN with NULL. If the subquery returns a single NULL, NOT IN returns no rows at all, while NOT EXISTS still works as expected. Rewrite the card around that case.

Study tip: merge the concept and syntax pairs

About nine pairs repeat one idea twice, as a definition card and a Syntax for X card: SELECT 4/5, WHERE 7/8, DISTINCT 19/20, INNER JOIN 22/23, GROUP BY 36/37, INSERT 53/54, UPDATE 55/56, DELETE 58/59. Combine each pair into one card with the German definition on top and the SQL statement underneath. Then write each query from memory on paper or in a SQL console before you flip the card. Reading the answer is not enough to learn the syntax.

Going back and forth between languages? The English version of this deck is covered in How to Master SQL Queries, Joins and Aggregates.

Search for OM9054 in the Flip It library to start reviewing.

Ready to learn faster? 🚀

Join FLIP IT for free and turn studying into a game.

Create my free account