Relational database

Preview

1. What is a relational database and how does it differ from other types of databases?
2. What are the primary components of a relational database, and how do they work together to store and retrieve data?
3. What are some common types of relationships that can be established between tables in a relational database, and how are they represented?
4. What are some common data integrity constraints that are typically used in relational databases, and how do they help ensure data accuracy and consistency?
5. What are some common best practices for designing and optimizing a relational database schema, and how can they improve performance and scalability?

Explain

A relational database is a type of database management system that organizes data into one or more tables with rows and columns. The relationships between the tables can be defined and maintained, allowing for complex queries and efficient data retrieval.

For example, consider a university database. The database could have separate tables for students, courses, and instructors. The student table would have columns for student ID, name, and major, while the course table would have columns for course ID, title, and instructor ID. The instructor table would have columns for instructor ID, name, and department.

By relating the tables with the instructor ID column, it is possible to find all courses taught by a specific instructor or all students enrolled in a specific course. This makes it easier to manage and query large amounts of data.

Keypoint

1. Relational database management systems (RDBMS) are used to store and manage data in a structured way.
2. Data is stored in tables, with each table containing rows and columns.
3. The columns in a table represent attributes or characteristics of the data or entities being represented, and the rows represent individual instances or records.
4. Relationships can be established between tables using foreign keys, which allow for data to be linked and queried across multiple tables.
5. SQL (Structured Query Language) is a common language used to interact with relational databases, allowing users to retrieve, manipulate, and analyze data.
6. Relational databases can be scaled vertically (adding hardware resources to a single database) or horizontally (distributing data across multiple databases).
7. Relational databases provide a high level of consistency and data integrity, preventing data from being duplicated or inconsistent across different records.
8. Relational databases are widely used across various industries, including finance, healthcare, and government.
9. While more complex than other database models, relational databases enable efficient data management and retrieval and are well-suited to handle large amounts of structured data.

Review

1. What is a primary key in a relational database?
   Answer: A primary key is a unique identifier for a row of data in a table, used to ensure that each row can be uniquely identified and accessed.

2. How is a foreign key used in a relational database?
   Answer: A foreign key is used to establish a relationship between two tables in a relational database. It refers to the primary key of another table and is used to ensure referential integrity and maintain consistency of data across tables.

3. What is normalization in a relational database?
   Answer: Normalization is the process of organizing data in a relational database by breaking it down into smaller, related tables, in order to minimize redundancy and improve efficiency of data retrieval and manipulation.

4. What is a join in a relational database?
   Answer: A join is an operation that combines data from two or more tables in a relational database into a single result set. It is typically used to retrieve data that is spread across multiple tables based on some common attribute.

5. What is the difference between a clustered and a non-clustered index in a relational database?
   Answer: A clustered index is an index in which the physical order of data in the table is organized based on the index key, whereas a non-clustered index is an index in which the physical order of data in the table is not dependent on the index key. Clustering the data can improve performance for certain types of queries, while non-clustered indexes are typically used for smaller tables or to index specific columns within larger tables.