A Level Computer Science: Database Management Systems — Practice Questions (Cambridge 9618)

These are original questions written for Marlbridge, for revision and practice on this content. They are not reproduced past-paper questions, and they do not replicate the exam’s exact structure, question count or mark tariffs — examination boards hold copyright in their own papers. Use these alongside the official past papers available free from your board.

Related: Databases study guide · Databases revision notes

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What do these questions practise? Section 8.2 Database Management Systems of the Cambridge International AS & A Level Computer Science 9618 syllabus (2027–2029): the features of a DBMS that address the problems of a file-based approach (data management and the data dictionary, data modelling, the logical schema, data integrity, and data security including backup and access rights) and how the developer interface and query processor are used.

Section A

1. State three problems of storing data using a file-based approach. [3]

2. Describe what is meant by a data dictionary and give three items it would contain. [4]

3. Explain what is meant by the logical schema of a database. [2]

4. State the purpose of data modelling in database design. [2]

Section B

5. A school stores student details in separate files for the library, the office and the exams department. Explain how using a DBMS would reduce two problems with this approach. [4]

6. Describe two ways in which a DBMS helps to maintain data integrity. [4]

7. Explain how a DBMS uses access rights to protect data, using the school database as an example. [3]

8. Describe a suitable backup procedure for a database that is updated throughout the school day. [3]

9. Describe the purpose of the developer interface in a DBMS. [2]

10. Explain the role of the query processor when a user runs a query. [3]

Section C

11. A small business is deciding whether to keep using spreadsheets saved as separate files or to move to a relational database managed by a DBMS. Evaluate the move, referring to the features of a DBMS. [6]

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Answers

1. Any three: data redundancy (the same data stored in several files) [1]; data inconsistency when copies are updated differently [1]; data dependence, where changing the file structure means changing every program that uses it [1]; difficulty sharing data between departments [1]; poor security, because whole files must be shared [1]; difficulty writing new queries across files [1].

2. A data dictionary is a file of metadata, that is, data about the data held in the database [1]. Any three items: table names [1]; field names [1]; data types and field sizes [1]; primary and foreign keys [1]; validation rules [1]; relationships between tables [1]; access rights [1].

3. The logical schema is the overall design or structure of the whole database, independent of the software and how data is physically stored [1], showing the tables, their fields, keys and the relationships between them [1].

4. To produce a model, such as an entity-relationship diagram, of the data to be stored and the relationships between data items [1], so that an appropriate database structure can be designed before it is built [1].

5. Any two developed: data is stored once in shared tables, so redundancy is reduced [1] and storage is saved [1]; because each item is stored once, an update applies everywhere, so inconsistency between departments’ copies is avoided [1–2]; programs access data through the DBMS, so changing the structure does not require every program to be rewritten (data independence) [1–2].

6. Any two: validation rules set in the DBMS check data as it is entered, for example a range check on a year group [1–2]; referential integrity ensures a foreign key value matches an existing primary key, so records cannot refer to non-existent records [1–2]; primary keys must be unique, so duplicate records cannot be created [1–2]; the DBMS controls simultaneous updates so that changes by two users do not conflict [1–2].

7. The DBMS stores which users or groups can read, insert, update or delete data in each table or view [1]. For example, teachers might be able to read and update exam results, while students can only read their own timetable [1]. Users must log in, and the DBMS refuses operations they are not authorised to carry out [1].

8. Full backup of the database each night when it is not in use [1]; incremental backups or a transaction log during the day so that recent changes can be recovered [1]; backups stored off-site or in the cloud and restoration tested regularly [1].

9. It allows a developer to create and modify the database structure, such as tables, queries, forms and reports, often through a visual interface rather than by writing all the code by hand [1], so that applications can be built for users without direct access to the underlying data [1].

10. The query processor takes the user’s query, for example in SQL [1], checks it and works out the most efficient way to carry it out, using indexes where available [1], then executes it against the database and returns the results to the user [1].

11. For: data is stored once, reducing redundancy and inconsistency [1]; the data dictionary and validation rules improve integrity [1]; access rights allow different staff to see only what they need [1]; the query processor makes it easy to combine data from several tables [1]; backup procedures are built in [1]. Against: cost of the software and of training [1]; time to design the schema and transfer data [1]; for very small amounts of data a spreadsheet may be sufficient [1]. A justified conclusion relating to the size and growth of the business is needed for full marks. Maximum 6.

Frequently asked questions

Is the data dictionary visible to ordinary users? Usually not; it is used by the DBMS and the database administrator to manage the structure.

Where do DDL and DML fit? They are section 8.3; this page focuses on the DBMS features in 8.2, which use DDL to define structure and DML to query and maintain data.

Based on the Cambridge International AS & A Level Computer Science 9618 syllabus for 2027, 2028 and 2029, section 8.2 Database Management Systems.