View source for PostgreSQL-Database/C2/Relational-Operators/English

'''Title of the Script: Relational Operators.'''

'''Authors: EduPyramids.'''

'''Keywords:''' postgresql, pgadmin4, Relational operators, equal to, not equal to, greater than, less than, greater than or equal to, less than or equal to, WHERE clause, edupyramids, video tutorial.

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|- 
|| '''Visual Cue'''
|| '''Narration'''
|- 
|| '''Slide 1'''

'''Title Slide'''
|| Welcome to this Spoken Tutorial on '''Relational Operators '''in''' Postgres Q L'''.
|- 
|| '''Slide 2 '''

'''Learning Objectives'''
|| In this tutorial, we will learn about
* '''Relational operators'''. 
|- 
|| '''Slide 3'''

'''System Requirements '''
* '''Ubuntu 24.04 LTS'''
* '''PostgreSQL version 18.1''', and
* '''PgAdmin 4 version 9.11'''
|| To record this tutorial, I am using the following setup.
|- 
|| '''Slide 4'''

'''Pre-requisites '''

[https://edupyramids.org/ https://EduPyramids.org]<span style="background-color:transparent;color:#000000;"> '''
|| To follow this tutorial,
* Learners should have '''Postgres Q L''' and '''p g Admin 4'''.
* For the prerequisite '''Postgres Q L''' tutorials, please visit this website. 
|- 
|| '''Slide 5'''

'''Code Files '''

The following code file is required to practice this tutorial:
* '''ro-commands.txt'''

This file is provided in the Code Files link on this tutorial page.

Please download and extract the file.
|| The following code file is required to practice this tutorial.

This file is provided in the Code Files link of this tutorial page.

Please download and extract the file.
|- 
|| 
|| Let us get started.
|- 
|| '''Slide 6'''

'''Relational operators'''

'''SELECT *'''

'''FROM students'''

'''WHERE city = ‘Bhopal’;'''


'''Highlight: WHERE'''
|| Relational operators are used to compare values in a table.

They are used along with the '''WHERE''' clause to filter the records.

They return only those rows that satisfy a specified condition.
|- 
|| '''Point to the interface.'''
|| I have opened the '''p g Admin 4 '''interface and connected to the localhost server.
|- 
|| 
|| Now let us use relational operators to execute queries with different conditions.
|- 
|| '''Type the following query:'''

'''SELECT *'''

'''FROM students'''

'''WHERE city = 'Delhi';'''

'''Highlight: WHERE city = 'Delhi';'''

Press the '''Execute''' '''query''' button.
|| Let us type this query.

In this query we will retrieve the records of students using equal to operator.

Click the Execute query icon to execute the query.

This query displays the details of the student Bindu, who resides in Delhi.
|- 
|| '''Type the following query:'''

'''SELECT *'''

'''FROM students'''

'''WHERE cgpa > 9.0;'''

Press the '''execute''' '''query''' button.
|| Next let us type this query.

Here we will retrieve the records of students whose C G P A is greater than 9 point zero.

Let us execute the query.

Output shows the details of students whose C G P A is greater than 9 point zero.
|- 
|| '''Type the following query:'''

'''SELECT *'''

'''FROM students'''

'''WHERE cgpa < 8.0;'''

Press the '''execute''' '''query''' button.
|| Next, let us type this query.

Here we will retrieve the records of students whose C G P A is less than 8 point zero.

Now execute this query to see the output.
|- 
|| '''Type the following query:'''

'''SELECT * FROM students'''

'''WHERE dob>= '1996-04-22';'''

Press the '''execute''' '''query''' button.
|| Let us now retrieve the records of students based on date of birth.

I will type the query that uses the greater than or equal to operator.

Then execute it.

The output displays all student records who were born on or after 22 April 1996.
|- 
|| '''Type the following query:'''

'''SELECT * FROM students'''

'''WHERE studentid <= 'S111';'''

Press the '''execute''' '''query''' button.
|| Next, let us retrieve the records of students whose student id is '''S 1 1 1 '''or less.

Let me type this query. 

Here we have used less than or equal to operator. 

Let us execute the query.

Notice the records of students in the table.
|- 
|| '''Type the following query:'''

'''SELECT *'''

'''FROM students'''

'''WHERE city <> 'Mumbai';'''

Press the '''execute''' '''query''' button.
|| Now, let us retrieve the records of students whose city is not Mumbai.

Let us type this query.

Here we have used the not equal to operator.

Now execute the query.

The output displays all students who are not from Mumbai. 
|- 
|| 
|| With this, we come to the end of this tutorial.
|- 
|| '''Slide 7 '''

'''Summary'''

In this tutorial, we learnt about
* Relational operators. 

|| Let us summarize.
|-
|| '''Slide 8 '''

'''Assignment'''

'''As an Assignment,'''
* Retrieve the details of students who reside in the city Pune.
* Display the details of students whose gender is Female.
* Retrieve the details of students who were born before 1st January 1996.
* Display the details of students whose student ID is not S101.
|| We encourage you to do this assignment.
|- 
|| '''Slide 9'''

'''This Spoken Tutorial is brought to you by EduPyramids Educational Services Private Limited, SINE, IIT Bombay.'''

'''Thank You'''
|| Thank you for joining.
|-
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