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SingaporeComputer Science

Data, Information and Databases

5 dot points across 5 inquiry questions. Click any dot point for a focused answer with worked past exam questions where available.

How do we organise tables to remove redundancy and avoid update anomalies?

Normalise a relational design to first, second and third normal form, explaining the anomalies each form removes
A focused answer to the H2 Computing outcome on normalisation. First, second and third normal form, the insertion, update and deletion anomalies they remove, and how to decompose a table step by step.
9 min answer →

How do we plan a database before building it, capturing entities and the relationships between them?

Model a problem domain with an entity-relationship diagram, identifying entities, attributes, relationships and cardinality, and map it to tables
A focused answer to the H2 Computing outcome on ER modelling. Entities, attributes and relationships, one-to-one, one-to-many and many-to-many cardinality, resolving many-to-many with a link table, and mapping an ER model to relational tables.
8 min answer →

How does a relational database organise data into tables, and how do keys link those tables together?

Describe the relational model in terms of tables, rows, attributes, primary keys and foreign keys, and explain referential integrity
A focused answer to the H2 Computing outcome on the relational model. Tables, rows and attributes, primary and foreign keys, relationships between tables, and how referential integrity keeps data consistent.
8 min answer →

How do we define the structure of a database and enforce rules on the data it can hold?

Define database schemas with CREATE TABLE, choosing data types and enforcing PRIMARY KEY, FOREIGN KEY, NOT NULL and UNIQUE constraints
A focused answer to the H2 Computing outcome on defining schemas. CREATE TABLE, choosing appropriate data types, and enforcing primary key, foreign key, NOT NULL and UNIQUE constraints to protect data integrity.
8 min answer →

How do we retrieve and change data in a relational database using SQL?

Write SQL queries using SELECT with WHERE, ORDER BY, JOIN, GROUP BY and aggregate functions, and modify data with INSERT, UPDATE and DELETE
A focused answer to the H2 Computing outcome on SQL queries. SELECT with WHERE and ORDER BY, joining tables, grouping with aggregate functions, and modifying rows with INSERT, UPDATE and DELETE.
9 min answer →