Types of databases (relational, NoSQL, object-oriented) in DBMS Theory - Step-by-Step Execution

Concept Flow - Types of databases (relational, NoSQL, object-oriented)

Start

↓

Choose Database Type

↓

Relational DB

↓

Tables with rows & columns

↓

NoSQL DB

↓

Flexible schema, key-value, document, graph

↓

Object-Oriented DB

↓

Store objects directly

↓

Use DB for data storage & retrieval

↓

End

This flow shows choosing between three main database types and their core characteristics before using them for data storage.

Execution Sample

DBMS Theory

SELECT * FROM Customers;
-- Relational DB query to get all customers

// NoSQL example: db.customers.find({})
// Object DB: store and retrieve objects directly

Shows example queries or actions for each database type to retrieve data.

Analysis Table

Step	Database Type	Data Structure	Query/Access Method	Example Output
1	Relational	Tables with rows and columns	SQL SELECT statements	Rows of customer data in table format
2	NoSQL	Flexible: key-value, document, graph	NoSQL queries (e.g., find())	JSON-like documents or key-value pairs
3	Object-Oriented	Objects with attributes and methods	Object methods or queries	Objects with properties and behaviors
4	End	-	-	Data retrieved according to DB type

💡 All database types provide data storage and retrieval but differ in structure and query methods.

State Tracker

Database Type	Structure	Query Method	Output Format
Relational	Tables	SQL	Rows/Columns
NoSQL	Documents/Key-Value/Graph	NoSQL Query	JSON-like or key-value
Object-Oriented	Objects	Object Methods	Objects

Key Insights - 3 Insights

Why does a relational database use tables instead of objects?

Relational databases organize data in tables with rows and columns for easy querying with SQL, as shown in execution_table row 1, unlike object databases that store data as objects.

How is NoSQL different from relational databases in data structure?

NoSQL databases use flexible structures like documents or key-value pairs (execution_table row 2), allowing schema changes without altering the whole database, unlike fixed tables in relational DBs.

What does it mean that object-oriented databases store objects directly?

It means data is stored as objects with attributes and methods (execution_table row 3), matching programming language objects, so no translation to tables is needed.

Visual Quiz - 3 Questions

Look at the execution_table, which database type uses SQL SELECT statements?

A Relational

B NoSQL

C Object-Oriented

D All of the above

💡 Hint

Check the 'Query/Access Method' column in execution_table row 1.

According to variable_tracker, which database type stores data as objects?

A Relational

B NoSQL

C Object-Oriented

D None

💡 Hint

Look at the 'Structure' column for each database type in variable_tracker.

At which step in execution_table do we see JSON-like documents as output?

A Step 1

B Step 2

C Step 3

D Step 4

💡 Hint

Refer to the 'Example Output' column in execution_table row 2.

Concept Snapshot

Types of Databases:
- Relational: Tables with rows/columns, use SQL queries.
- NoSQL: Flexible schema, stores documents, key-value, or graphs.
- Object-Oriented: Stores objects directly with attributes/methods.
Each type suits different data and application needs.

Full Transcript

This lesson shows three main types of databases: relational, NoSQL, and object-oriented. Relational databases organize data in tables and use SQL to query data. NoSQL databases use flexible structures like documents or key-value pairs and have different query methods. Object-oriented databases store data as objects directly, matching programming language objects. The execution table shows examples of data structures, query methods, and outputs for each type. The variable tracker summarizes their key differences. Key moments clarify common confusions about data structure and query methods. The quiz tests understanding by referencing the execution visuals.