Databases

Question 1

Name two types of DBMS

Answer 1

RDBMS
NoSQL

Question 2

What is an RDBMS, examples, and the use cases

Answer 2

1. Relational Database Management Systems (RDBMS)
   
   • Description: Stores data in structured tables with rows and columns, following a predefined schema.
   • Examples: MySQL, PostgreSQL, Oracle, Microsoft SQL Server.
   • Use Case: Applications requiring complex queries, transaction management, and strong consistency.

Question 3

What is NoSQL

Answer 3

2. NoSQL Database
   
   • Description : Flexible, schema-less databases for handling unstructured or semi-structured data.
   • Types:
     
     • Document-based: MongoDB
     • Key-value: Redis
     • Column-based: Cassandra
     • Graph-based: Neo4j
     • Use Case: Big data, real-time analytics, highly scalable applications.

Question 4

What does an RDBMS do basically

Answer 4

the “relational” aspect refers to the relationships between tables. These relationships are established using keys (primary keys and foreign keys), which connect data across different tables in a structured and organized way.

Question 5

Characteristics of Primary Keys

Answer 5

• Definition: A column (or set of columns) that uniquely identifies each record in a table.
• Key Points:
  
  • Must contain unique values.
  • Cannot contain NULL values.
  • Each table can have only one primary key.
• Purpose: Ensures that each row in the table is unique.
• Example: In a Students table, StudentID is the primary key that uniquely identifies each student.

Question 6

Foreign Key

Answer 6

• A column (or set of columns) in one table that creates a link to the primary key of another table. It establishes the relationship between the two tables.
• Key Points:
  
  • Can contain duplicate values.
  • Can contain NULL values (unless restricted by a NOT NULL constraint).
  • A table can have multiple foreign keys.
• Purpose: Maintains referential integrity between tables by linking rows from one table to another.
• Example: In an Enrollments table, StudentID is a foreign key that references StudentID in the Students table.

Question 7

Types of relationships

Answer 7

• One-to-One: Each record in one table is linked to only one record in another table.
  
  • Example: A Person table might have a one-to-one relationship with a Passport table (one person, one passport).
• One-to-Many: A record in one table is related to multiple records in another table.
  
  • Example: A Teacher table could have a one-to-many relationship with a Class table (one teacher teaches multiple classes).
• Many-to-Many: Multiple records in one table are related to multiple records in another table, typically handled with a junction or associative table.
  
  • Example: A Students table and a Courses table might have a many-to-many relationship, managed by an Enrollments table (many students enroll in many courses).

Question 8

Why do we even have keys in RDBMS

Answer 8

• To make a connection between the data
• To locate and collect the unique data that we require

Question 9

What does SQL stand for

Answer 9

Structured Query Language

Question 10

What does SQL do vele

Answer 10

Helps access and manipulate your databases

Question 11

What is ANSISQL

Answer 11

• A standardized version of SQL for managing and manipulating databases.
• Ensures consistency across different database management systems (DBMS).

ANSI SQL promotes a consistent, flexible, and efficient approach to database management, making it essential for developers and data professionals.