Data Structures & Databases is a core part of IB Computer Science. Revise the key concepts and common mistakes below, then lock them in with the free games.
Key concepts
StackLIFO structure with push/pop; used in call stacks, expression evaluation, undo features.
QueueFIFO structure with enqueue/dequeue; used in scheduling, breadth-first search, print spoolers.
Linked listSequence of nodes with data and pointer to next; dynamic size; O(n) access.
Binary treeHierarchical structure with up to two children per node; balanced trees give O(log n) operations.
Hash tableKey-value store using hash function; average O(1) lookup; collisions handled by chaining or open addressing.
GraphVertices and edges; directed/undirected, weighted; algorithms include Dijkstra (1959) shortest path.
TableRelation: rows and named columns.
Row/TupleSingle record in a table.
Primary keyUnique identifier for each row.
Foreign keyReferences primary key of another table.
EntityReal-world object represented as a table.
ER diagramModels entities and their relationships.
1NFAtomic values, no repeating groups.
2NF1NF + no partial dependence on key.
Common mistakes to avoid
Questions where students often pick the tempting wrong answer — make sure you know the right one:
How does a stack remove items?✗ First in, first out (FIFO). ✓ Last in, first out (LIFO).
How does a queue remove items?✗ Last in, first out (LIFO). ✓ First in, first out (FIFO).
What is a primary key?✗ A field that can have duplicate values. ✓ A field that uniquely identifies each record in a table.
What does SQL do?✗ Designs the physical hardware. ✓ Lets you query and manage data in a relational database.
Practise Data Structures & Databases — free games
Test yourself with these quick revision games for this topic:
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