IB Computer Science - Databases (Option A)

A.1.5 Define the term database transaction.

A database transaction is a logical unit of work that comprises one or more database operations (such as inserts, updates, or deletes). The primary purpose of a transaction is to ensure the consistency, integrity, and atomicity of database operations.

Durability

Durability guarantees that once a transaction is committed, its effects on the database are permanent and will survive subsequent failures, such as system crashes or power outages. This property is crucial for data recovery and ensures that the changes made by committed transactions persist, providing a reliable and robust database system.

A.1.4 Describe the use of transactions, states and updates to maintain data consistency (and integrity).

For example, to ensure data consistency when moving money between two accounts it is necessary to complete two operations (debiting one account and crediting the other). Unless both operations are carried out successfully, the transaction will be rolled back. For example, ensuring correct information relating to customers and/or clients.

A.1.2 Outline the differences between an information system and a database.

These terms are not synonymous. Databases are a component within an information system.

A.1.3 Discuss the need for databases.

This should address topics such as the benefits of data sharing. For example, correct information relating to customers and/or clients.

A.1.7 Explain the importance of the ACID properties of a database transaction.

ACID refers to: • atomicity • consistency • isolation • durability.

Atomicity

Atomicity ensures that a transaction is treated as a single, indivisible unit of work. Either all the operations within the transaction are completed successfully, or none of them are. This property is crucial because it prevents transactions from leaving the database in a state of partial completion, which could lead to data inconsistency or errors.

A.1.6 Explain concurrency in a data sharing situation.

Concurrency in a data sharing situation refers to the ability of multiple users or processes to access and manipulate data simultaneously within a shared database or system. In a multi-user environment, where several users or applications interact with the same database concurrently, managing concurrency becomes crucial to ensure data consistency, integrity, and isolation.

Consistency

Consistency ensures that a transaction brings the database from one valid state to another. It enforces integrity constraints and business rules, maintaining the overall correctness of the database. Consistency is essential for preventing the database from entering invalid or contradictory states due to incomplete or incorrect transactions.

A.1.9 Explain the role of data validation and data verification.

Data Validation: Checking and ensuring that entered data is accurate, follows specific rules, and is in the right format. Data Verification: Confirming the accuracy and authenticity of received data to ensure it is reliable and trustworthy. Be sure to explain the two in depth.

A.1.1 Outline the differences between data and information.

Data is meaningless. To be useful, data must be interpreted to produce information.

Isolation

Isolation ensures that the operations of one transaction are isolated from the operations of other concurrent transactions. This prevents interference or conflicts between transactions. It's important to avoid situations where the outcome of a transaction depends on the intermediate state of another, leading to potential inconsistencies or errors.

A.1.8 Describe the two functions databases require to be performed on them.

Query functions and update functions.