Securing a database aims to achieve the following objectives Data Confidentiality Data Integrity Availability Briefly describe what is meant by each of the above objectives. In each name one security controls that can be applied in Database (9marks) ii. Discuss THREE methods of backups used in database (6marks) iii. Discuss FIVE Properties of a Primary Key (5marks)

i. **Objectives of Securing a Database:**<br /><br />1. **Data Confidentiality:**<br /> - This objective ensures that sensitive information is accessible only to authorized users and is protected from unauthorized access or disclosure. <br /> - **Security Control:** Encryption can be applied to protect data confidentiality by encoding the data so that only authorized users with the decryption key can access it.<br /><br />2. **Data Integrity:**<br /> - Data integrity ensures that the data remains accurate, consistent, and reliable over its lifecycle. It prevents unauthorized alterations to the data.<br /> - **Security Control:** Checksums or hash functions can be used to verify the integrity of data by detecting any unauthorized changes.<br /><br />3. **Availability:**<br /> - Availability ensures that database services are accessible to authorized users whenever needed, without undue delay.<br /> - **Security Control:** Implementing redundancy and failover systems can help maintain availability by ensuring that there are backup systems in place in case of hardware or software failures.<br /><br />ii. **Methods of Backups Used in Databases:**<br /><br />1. **Full Backup:**<br /> - A full backup involves copying the entire database, including all data files, system files, and transaction logs. It provides a complete snapshot of the database at a specific point in time.<br /><br />2. **Incremental Backup:**<br /> - Incremental backups only capture the data that has changed since the last backup (whether it was a full or another incremental backup). This method saves storage space and reduces backup time.<br /><br />3. **Differential Backup:**<br /> - Differential backups involve backing up all the data that has changed since the last full backup. Unlike incremental backups, differential backups grow larger over time until the next full backup is performed.<br /><br />iii. **Properties of a Primary Key:**<br /><br />1. **Uniqueness:**<br /> - A primary key must contain unique values for each record in the table, ensuring that no two rows have the same primary key value.<br /><br />2. **Non-nullability:**<br /> - A primary key cannot contain null values. Every record must have a valid primary key value to ensure entity integrity.<br /><br />3. **Immutability:**<br /> - Once assigned, the value of a primary key should not change. This stability helps maintain consistent references across related tables.<br /><br />4. **Minimality:**<br /> - The primary key should consist of the smallest number of columns necessary to maintain uniqueness. It should not include unnecessary attributes.<br /><br />5. **Single Column or Composite:**<br /> - A primary key can be a single column or a combination of multiple columns (composite key) if needed to ensure uniqueness.