Chapter A3 · 12 available objectives
Databases
Relational design, normalization, SQL, and data operations.
Explain the features, benefits and limitations of a relational database
A relational database stores data in tables . Each table is made up of: records (row = record = tuple = instance) each row stores one complete item fields…
3 minA3.2.1Describe database schemas
A database schema is the blueprint of a database. It identifies: the entities (tables) the attributes (fields) the relationships between entities the…
1 minA3.2.2Construct ERDs
An ERD (Entity Relationship Diagram) shows: entities attributes relationships cardinality modality ERDs are used to design a relational database before…
2 minA3.2.3Outline the different data types used in relational databases
Common relational database data types can be grouped into: string data types numeric data types date/time data types
2 minA3.2.4Construct tables for relational databases
A relational table should: represent one entity have a primary key use suitable data types include foreign keys where relationships exist avoid repeating…
1 minA3.2.5Explain the difference between normal forms
If you want one sentence for normalization, use: the data should depend on the key, the whole key, and nothing but the key
2 minA3.2.6Construct a database normalized to 3NF for a range of real-world scenarios
To normalize a database to 3NF : 1. Start with the unnormalized data 2. identify the primary key 3. remove repeating groups to reach 1NF 4. remove partial…
2 minA3.2.7Evaluate the need for denormalizing databases
Denormalization means intentionally adding some redundancy back into a database. It is usually done to improve performance.
1 minA3.3.1Outline the differences between data language types within SQL
Data Definition Language (DDL) is used to create and modify the structure of the database it is used to create the schema, tables, and constraints common…
2 minA3.3.2Construct queries between two tables in SQL
This section also includes some common SQL commands beyond the bare minimum textbook examples.
3 minA3.3.3Explain how SQL can be used to update data in a database
INSERT INTO , UPDATE , and DELETE are all DML commands. They do not use the TABLE keyword.
1 minA3.3.4Construct calculations within a database using SQL’s aggregate functions
Aggregate functions allow calculations to be performed on data in a database.
1 min