Mastering Database Concepts

What is a primary key in a database?

• A primary key is a type of foreign key in a database.

• A primary key is used to store large amounts of data in a database.

• A primary key can have duplicate values in a database.

• A primary key is a unique identifier for a record in a database.

Explain the difference between SQL and NoSQL databases.

• SQL databases are relational with a fixed schema; NoSQL databases are non-relational with flexible schemas.

• SQL databases are designed for unstructured data.

• NoSQL databases require a predefined schema.

• SQL databases are non-relational with a fixed schema.

What is normalization in database design?

• A method to increase data redundancy

• A way to merge multiple databases into one

• Normalization in database design is the process of organizing data to minimize redundancy and dependency.

• A technique for data encryption

Define a foreign key and its purpose.

• A foreign key is a field that links two tables by referencing the primary key of another table, ensuring data integrity.

• A foreign key is a field that stores data without any relationship to other tables.

• A foreign key is a type of primary key used in the same table.

• A foreign key is a unique identifier for a single table.

What is a database index and why is it used?

• A database index is a data structure that improves the speed of data retrieval operations.

• A database index is a method for encrypting data.

• A database index is a type of database backup.

• A database index is used to store data permanently.

What are the ACID properties in database transactions?

• Atomicity, Clarity, Isolation, Reliability

• Atomicity, Consistency, Isolation, Accessibility

• Accuracy, Clarity, Integrity, Timeliness

• ACID properties: Atomicity, Consistency, Isolation, Durability.

Explain the concept of a join in SQL.

• A join in SQL combines rows from two or more tables based on a related column.

• A join in SQL is a method to sort data within a single table.

• A join in SQL is used to create new tables from existing ones.

• A join in SQL deletes rows from one table based on another.

What is a stored procedure?

• A stored procedure is a temporary table used for data storage.

• A stored procedure is a precompiled collection of SQL statements stored in a database.

• A stored procedure is a single SQL statement executed on demand.

• A stored procedure is a type of database index.

What is the purpose of a database schema?

• The purpose of a database schema is to define the organization and structure of data within a database.

• To create user interfaces for applications.

• To manage network security protocols.

• To store data in a cloud environment.

Describe the difference between a database and a data warehouse.

• A database is used for data backup, while a data warehouse is for data entry.

• A database is for real-time transactions, while a data warehouse is for analytical processing of historical data.

• A database stores only historical data, while a data warehouse handles real-time transactions.

• A database is a type of data warehouse that focuses on big data analysis.