Introduction to Databases, ER Modeling, Relational Algebra

What is a database?

An organized collection of data.

What is the importance of a database?

To provide efficient storage and retrieval of data.

What are the different types of databases?

Relational, NoSQL, object-oriented, etc.

What are the components of a database?

Data, schema, DBMS, users, and hardware.

What are some advantages of using a database?

Data consistency, security, and scalability.

What are some disadvantages of using a database?

Complexity, cost, and maintenance.

What is ER modeling?

A graphical representation of entities and relationships used to design and understand the structure of a database.

What is the purpose of ER modeling?

To design and understand the structure of a database.

What are entities in ER modeling?

Objects with distinct properties.

What are attributes in ER modeling?

Characteristics of entities.

What are relationships in ER modeling?

Connections between entities.

What is cardinality in ER modeling?

The number of entities involved in a relationship.

What are ER diagrams?

A visual representation of entities and relationships.

What is relational algebra?

A mathematical operation used for manipulating and retrieving data from relational databases.

What is the purpose of relational algebra?

To manipulate and retrieve data from databases.

What are the basic operations in relational algebra?

Selection, projection, union, intersection, difference, and Cartesian product.

What is selection in relational algebra?

Filtering data based on a condition.

What is projection in relational algebra?

Selecting specific attributes from a relation.

What is union in relational algebra?

Combining data from two relations, keeping only distinct tuples.

What is intersection in relational algebra?

Combining data from two relations, keeping only common tuples.

What is difference in relational algebra?

Finding tuples that are in one relation but not the other.

What is Cartesian product in relational algebra?

Combining data from two relations, creating all possible pairs.

What are join operations in relational algebra?

Inner join, outer join, and natural join.

What is inner join in relational algebra?

Combining data from two relations, keeping only the common tuples.

What is outer join in relational algebra?

Combining data from two relations, keeping all tuples from one relation and matching tuples from the other relation.

What is natural join in relational algebra?

Combining data from two relations, keeping only the common tuples and eliminating the duplicate columns.

What is division operation in relational algebra?

Retrieving data that matches a set of conditions.

What is a primary key in a database?

A unique identifier for a row in a table.

What is a foreign key in a database?

A key in one table that refers to the primary key of another table.

What is normalization in a database?

The process of organizing data in a database to minimize redundancy and dependency.

What is denormalization in a database?

The process of adding redundant data to a database to improve performance.

What is a transaction in a database?

A unit of work performed by a user that involves one or more database operations.

What is a rollback in a database?

Undoing the changes made in a transaction.

What is a commit in a database?

Saving the changes made in a transaction.

What is the purpose of ER modeling?

The purpose of ER modeling is to design and understand database structure.

What are the components of an ER diagram?

The components of an ER diagram are entities, attributes, and relationships.

What is the difference between a left outer join and a right outer join?

A left outer join returns all the rows from the left table and matching rows from the right table, while a right outer join returns all the rows from the right table and matching rows from the left table.

What is the purpose of the selection operation in relational algebra?

The purpose of the selection operation is to filter data based on a condition.

What is the difference between a NoSQL database and a relational database?

A NoSQL database is a non-relational database that does not use a fixed schema, while a relational database is a structured database that uses tables with predefined relationships between them.

What is a Cartesian product in relational algebra?

A Cartesian product is a binary operation that returns a table containing all possible combinations of rows from two input tables.