Database Concepts

Databases · 5 question types

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Exam Frequency Analysis

Past paper frequency (2018 to 2024)

This topic accounts for approximately 4% of your exam marks.

stable

Rare

Stable4%

SQL SELECT queries and database structure (tables, fields, records) appear as 4 to 6 mark questions.

A database is an organised collection of data, stored on secondary storage in a way that lets a program retrieve, update and analyse it efficiently.

The focus here is on single-table databases: just one rectangular table of data with named columns (called ) and one row per real-world item (called ).

Databases vs plain text files

Text files were covered in topic 23. The same data could be stored either way; databases offer several advantages. In a plain text file, each item's fields are simply written on consecutive lines, and one such group of lines is a single record:

A plain text file named Employees.txt in which each item is stored as four consecutive lines (name, department, salary, age); two of these four-line groups are outlined and labelled as a record. — Source: Database by Save My Exams

Feature	Plain text file	Database
Data organisation	Lines of text; the program decides what each line means	Named fields, rows, and column data types
Searching	Read every line in turn (linear)	Indexed lookup; very fast even with millions of records
Concurrent access	Awkward; one writer at a time	Built-in support for many users at once
Validation	Done by the program reading the file	Validation rules on each field at the database level
Security	Limited; depends on the OS	Per-user access controls, encrypted at rest, audited
Best for	Small amounts of structured text data	Large, structured data accessed by many users

For a school's collection of student grades, a database is almost always the right tool. For a small configuration file, a plain text file may be enough.