Database II - SS3 ICT Past Questions and Answers - page 2
What does the term "Normalization" mean in the context of databases?
Making data less secure
Organizing data efficiently by reducing redundancy and data anomalies
Adding more data to a database
Deleting data from a database
What is the purpose of a database backup?
To make the database run faster
To permanently delete data
To prevent data loss by creating a copy of the database
To hide sensitive data
Which SQL statement is used to add new records to a database table?
MODIFY
INSERT INTO
CREATE TABLE
DELETE FROM
What does SQL JOIN do?
Combine data from multiple tables based on a related column
Delete data from a table
Add new columns to a table
Create a new database
What is the purpose of database indexes?
To store large files
To physically arrange data in the database
To optimize query performance by allowing faster data retrieval
To categorize data
Explain the concept of database normalization
Database normalization is a process in database design that involves organizing data in a way that reduces redundancy and data anomalies (such as update anomalies, insert anomalies, and delete anomalies). The main goal is to structure the database schema to minimize data duplication and ensure data integrity. This is achieved by dividing tables into smaller, related tables and establishing relationships between them using primary keys and foreign keys. The normalization process is typically divided into several normal forms, such as First Normal Form (1NF), Second Normal Form (2NF), and so on, with each level addressing specific types of data redundancy and dependency issues.
Describe the steps involved in creating a new table in a database: Creating a new table in a database involves several steps
Determine the Table's Purpose: Define what the table will store, its columns, and the type of data it will hold.
Choose a Suitable Data Type: Specify the data type for each column (e.g., text, integer, date).
Define Constraints: Set constraints like primary keys, unique constraints, and foreign keys to ensure data integrity.
Write the SQL Statement: Use SQL (Structured Query Language) to create the table, specifying column names, data types, and constraints.
Execute the SQL Statement: Run the SQL command to create the table within the database.
Verify the Table: Check that the table has been created correctly by examining its structure.
How can you improve the performance of database queries: Database query performance can be enhanced through various strategies?
Indexing: Create indexes on columns frequently used in queries to speed up data retrieval.
Optimizing Queries: Write efficient SQL queries that use appropriate joins and filtering conditions.
Database Design: Ensure a well-structured database schema with normalized tables to reduce redundant data.
Caching: Use caching mechanisms to store frequently accessed query results in memory.
Hardware Upgrades: Improve server hardware, such as increasing RAM or using faster storage devices.
Load Balancing: Distribute database load across multiple servers using load balancing techniques.
Partitioning: Partition large tables to divide data into more manageable segments.
Why is it important to perform regular database backups, and how would you restore a database from a backup?
Regular database backups are essential for data protection and recovery in case of data loss due to various reasons like hardware failures, data corruption, or human errors. Backups serve as a snapshot of the database at a specific point in time.
To restore a database from a backup:
Identify the backup source, whether it's a full backup, incremental backup, or differential backup.
Ensure that the database server is in the correct state for restoration.
Use the appropriate command or tool provided by the DBMS to restore the backup, specifying the backup file or location.
Follow any additional instructions related to log files or transaction logs, depending on the type of backup.
Verify the restored database to ensure data integrity and consistency.
The specific steps and commands can vary depending on the database management system being used.