A-Level Computer Science Data Questions: This question type doesn't exist. How to study and practice the Data Representation and Databases chapters in Paper 1.

First, a clarification: Cambridge A-Level Computer Science (9618) does not have a question type called "data questions", and Edexcel IAL does not offer Computer Science either. However, in the AS Paper 1 theory paper, two chapters specifically focus on "data": Chapter 1 Data Representation (number systems, characters, images, sound, compression) and Chapter 8 Databases (relational databases, normalization, SQL). The questions in these two chapters mainly involve calculations, conversions, and writing SQL. They are the most "hands-on" part of Paper 1, and calculators are not allowed for the entire paper. In our article on How A-Level Computer Science is Tested, we only listed the chapter names. For floating-point numbers and file organization at A Level, please see Article 218. This article is organized item by item based on the Cambridge 9618 syllabus (the content of these two chapters is the same in the 2026 and 2027–2029 versions), accompanied by examples we have written.

1. Where It Is Tested

• Paper 1 Theory Fundamentals: 1 hour 30 minutes, 75 marks, all questions compulsory, covering Chapters 1–8, accounting for 50% of AS and 25% of A Level;
• Calculators are not allowed in any paper, so number system conversions and file size estimations must be done by hand;
• Chapter 8 (including SQL) is within the scope of Paper 1 (Chapters 1–8); Paper 2 covers Chapters 9–12, and Paper 4 covers Chapters 19–20, neither of which includes Chapter 8.

2. Chapter 1 Data Representation: Syllabus Requirements

1.1 Data Representation

• Differences between binary and decimal prefixes: kibi vs. kilo, mebi vs. mega, gibi vs. giga, tebi vs. tera (1 KiB = 1024 bytes, 1 kB = 1000 bytes);
• Number systems: binary, denary, hexadecimal, BCD (Binary-Coded Decimal), and one's and two's complement; ability to convert integers between various bases and representations;
• Binary addition and subtraction: including positive and negative numbers, understanding how overflow occurs;
• Practical applications of BCD and hexadecimal;
• Character encoding: familiarity with ASCII, extended ASCII, and Unicode; the syllabus notes that memorizing specific character codes is not required.

1.2 Multimedia

• Bitmaps: pixels, file headers, image resolution, screen resolution, color depth (bit depth); estimating bitmap file sizes; the effect of changing resolution or color depth on image quality and file size;
• Vector graphics: drawing objects, properties, drawing lists; justifying the choice between bitmap and vector graphics for a given task;
• Sound: sampling, sampling rate, sampling resolution, analog and digital data; the effect of changing sampling rate and resolution on file size and accuracy.

1.3 Compression

• Why compression is needed, along with examples of its use;
• Lossy and lossless compression, and the ability to choose a method for a given scenario and justify the choice;
• How text, bitmap, vector, and sound files are compressed, including Run-Length Encoding (RLE).

3. Chapter 1: A Few Examples

The following examples are written by us, not exam questions, and are used to illustrate the algorithms required by the syllabus.

• Two's complement: Represent −5 in 8-bit two's complement. First, write 5 = 00000101, invert the bits to get 11111010, then add 1 to get 11111011;
• BCD: The BCD for decimal 59 encodes each digit separately: 5 → 0101, 9 → 1001, resulting in 0101 1001;
• Hexadecimal: Binary 1011 0110 grouped in fours: 1011 = B, 0110 = 6, resulting in B6;
• Bitmap file size: 800 × 600 pixels, 24-bit color depth: 800 × 600 × 24 = 11,520,000 bits = 1,440,000 bytes, approximately 1.44 MB (using base 1000), or 1,440,000 ÷ 1024 = 1406.25 KiB (using base 1024). Pay attention to which unit the question asks for; if the question requires considering the file header, add its size;
• Sound file size: Mono, 44,100 Hz sampling rate, 16-bit sampling resolution, 60 seconds duration: 44,100 × 16 × 60 = 42,336,000 bits = 5,292,000 bytes, approximately 5.29 MB;
• Run-Length Encoding: The string AAAABBBCC can be recorded as "4A 3B 2C" (the notation varies by question, so write it in the format given in the question).

4. Chapter 8 Databases: Syllabus Requirements

8.1 Database Concepts

• The limitations of file-based storage, and how relational databases solve these problems;
• Terminology: entity, table, record, field, tuple, attribute, primary key, candidate key, alternate key, foreign key, relationships (one-to-many, one-to-one, many-to-many), referential integrity, index;
• Recording database design using Entity-Relationship diagrams (E-R diagrams);
• Normalization: First, Second, and Third Normal Forms (1NF, 2NF, 3NF); explaining whether a given table meets 3NF; designing a normalized database based on a description, given data, or a given table.

8.2 Database Management Systems (DBMS)

• DBMS functions for solving file storage problems: data management (including maintaining the data dictionary), data modeling, logical schema, data integrity, data security (including backups and setting access permissions by user or user group);
• Software tools in a DBMS: developer interface, query processor.

8.3 DDL and DML

• A DBMS uses Data Definition Language (DDL) to create and modify database structures, and Data Manipulation Language (DML) to query and maintain data; the industry standard for both is SQL;
• DDL (read and write simple statements): CREATE DATABASE; CREATE TABLE, with attribute data types including CHARACTER, VARCHAR(n), BOOLEAN, INTEGER, REAL, DATE, TIME; ALTER TABLE; adding a primary key PRIMARY KEY (field); adding a foreign key FOREIGN KEY (field) REFERENCES Table (Field);
• DML (write SQL scripts, involving a maximum of two tables): queries include SELECT … FROM, WHERE, ORDER BY, GROUP BY, INNER JOIN, SUM, COUNT, AVG; data maintenance includes INSERT INTO, DELETE FROM, UPDATE.

5. Chapter 8: A Few Examples

The following examples are written by us and are not exam questions.

CREATE TABLE Student (
    StudentID INTEGER,
    Name VARCHAR(30),
    ClassID CHARACTER,
    PRIMARY KEY (StudentID),
    FOREIGN KEY (ClassID) REFERENCES Class (ClassID)
);

SELECT Name
FROM Student
WHERE ClassID = 'A'
ORDER BY Name;

SELECT Class.Room, COUNT(Student.StudentID)
FROM Student INNER JOIN Class ON Student.ClassID = Class.ClassID
GROUP BY Class.Room;

Approach to determining normalization (our explanation, subject to textbooks and marking schemes): 1NF—each field stores only one value, with no repeating groups; 2NF—meets 1NF, and non-key attributes are fully dependent on the entire primary key (no attributes depend on only part of a composite primary key); 3NF—meets 2NF, and there are no dependencies among non-key attributes (no transitive dependencies). When determining this, first identify the primary key, then check what each non-key attribute depends on.

6. How to Practice

Here are some empirical suggestions:

1. Be proficient in manual calculations: Since calculators are not allowed, practice conversions and addition/subtraction for binary, hexadecimal, two's complement, and BCD repeatedly, especially overflow detection in two's complement;
2. Clarify units first: For file size questions, first confirm whether the question asks for bits, bytes, KB, or KiB, and write down the units for each step;
3. Answer "impact" questions in pairs: For example, increasing the sampling rate makes the file larger and the sound more accurate; increasing the color depth provides more colors and makes the file larger;
4. Write SQL according to the syllabus subset: The syllabus lists the statements to be mastered; practice within this scope, paying attention to the join conditions for INNER JOIN and its combination with GROUP BY;
5. Practice normalization with "given data, produce design": Start with a messy table, break it down step by step into 3NF tables, and identify the primary and foreign keys;
6. Use accurate terminology: Use the syllabus terminology for primary key, candidate key, foreign key, referential integrity, data dictionary, etc.

Conclusion

Computer Science does not have a separate "data question" category, but the Data Representation and Databases chapters in Paper 1 are exactly the questions that deal with data: number system conversions, file size estimations, compression method selection, E-R diagrams, normalization, and SQL. These two chapters focus mainly on calculations and operations. As long as you practice the methods thoroughly and write the units and terminology accurately, they are stable scoring points. If you need A-Level Computer Science tutoring, feel free to chat with our teachers.

Verification note: This article was verified in September 2026: the duration, marks, scope, and weighting of Paper 1, the fact that calculators are not allowed in all papers, and all requirements and instructions for Chapter 1 (1.1–1.3) and Chapter 8 (8.1–8.3) (including that memorizing character codes is not required, the list of SQL data types and statements, and that DML involves a maximum of two tables) are from Cambridge International's "Computer Science 9618 syllabus for 2027, 2028 and 2029", and have been checked line by line against the "2026" version; the content of these two chapters is identical. The fact that Edexcel IAL does not offer a Computer Science course has been verified in Article 170 on this site. The examples for two's complement, BCD, hexadecimal, file size, run-length encoding, and SQL are written by us and are not exam questions; the explanation and practice methods for normalization are our empirical suggestions.

References:

• Cambridge International: Computer Science 9618 Syllabus 2026 (PDF)
• Cambridge International: Computer Science 9618 Syllabus 2027–2029 (PDF)