Most Asked SQL Interview Question - Solved Using 3 Methods

In this video, we will learn solving a most asked SQL interview question, which was asked in Google, Amazon and Uber interview. We will solve this question using 3 different methods.

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Timestamp:
00:00 Intro
00:17 SQL Interview Question
01:30 Method 1- SQL Query Solution
06:51 Method 2- SQL Query Solution
11:28 Method 3- SQL Query Solution
14:26 Outro

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If this is the first ever video you're watching allow me to introduce myself, Hey I'm Rishabh Mishra and currently working as Senior Data Analyst at Bangalore. On this channel I like to guide and help my juniors and data science aspirants regarding Data Science jobs and useful tips for college students.
Have a great day buddy!

#sqlinterviewquestions #sqlinterviewquestionsandanswers

[NidaHasan-hn]

create table travel (
source varchar(50),
destination varchar(50),
distance int);

insert into travel (source, destination, distance)
values
('Mumbai', 'Bangalore', 500),
('Bangalore', 'Mumbai', 500),
('Delhi', 'Mathura', 150),
( 'Mathura', 'Delhi', 150),
('Nagpur', 'Pune', 500),
( 'Pune', 'Nagpur', 500);

[subhradipbarik]

In the first approach without doing group by and all, we can just apply distinct after greatest and and least things

[alenb]

In method 1 using Greatest() and Least(), in our output (6:00) 3rd column we are getting Pune -> Nagpur but we are required to show(0:21) Nagpur -> Pune.

[shivendusharma]

Mishra ji 🙏, you are wonderful teacher and it is reflected in your videos. 🙂 It is also evident from your prof. experience.

[JALAL-bs]

We can also use greatest destination and apply distinct

[shraddhadhakad]

Using greatest and least method

select greatest(source, destination), least(source, destination), max(distance)
from travel
group by greatest(source, destination), least(source, destination);

[NiteshKumar-yskq]

Bhaiya direct bhi ho skta h na ye to
Select * from travel Where source>deatination;
Aise

[ishika]

with cte as(
select 1 as id, source, destination, distance
from travel
union all
select 2 as id, destination, source, distance
from travel)
select * from cte
where source>destination and id=1

[floyedmoras]

Hi Rishabh, I was trying with multiple methods and i found if we use the query like
select *
from Travel
where source > destination;
the answer would be the same and this is the shortest method. though i m not sure if there is any discrepancy with this query, Please clarify or suggest.

[rahulnegi]

using cte :

with cte1 as
(select source, row_number() over(order by (select null)) as rn_s
from travel
)

select t1.source, t1.destination, t1.distance from travel as t1
join
(
select c1.source as source, c2.source as destination from cte1 c1
join cte1 c2
where c1.source <> c2.source and c1.rn_s < c2.rn_s
) as t2
on t1.source = t2.source and t1.destination = t2.destination ;

[govindshah]

Please find the code to create the mentioned table in this tutorial:

create table travel (
source varchar(50),
destination varchar(50),
distance varchar(50));

insert into travel (source, destination, distance)
values
('Mumbai', 'Bangalore', 500),
('Bangalore', 'Mumbai', 500),
('Delhi', 'Mathura', 150),
( 'Mathura', 'Delhi', 150),
('Nagpur', 'Pune', 500),
( 'Pune', 'Nagpur', 500);

[vinaygupta]

hi, love your teaching technique, please make a video on advance power bi interview Q&A. it will really appreciated.
thankyou

[hassamulhaq]

I go with inner join. Method 2.

Method 3 slightly difficult.

[proud_indian]

Hello Rishabh, Thanks for creating such simple explanation for complex problems, Your approach was really easy to understand. I have seen the same question on other youtube channels but it was quite difficult for me to understand the same problem.

[venuamrutham]

My personal two methods,
M1:
select distance, GROUP_CONCAT(source) from (select distinct * from table) as sub_query
GROUP BY distance; (:: "select distinct * from table" important if you have original duplicates cities pair)
M2:
select DISTINCT greatest(source, destination) as "from", least(source, destination) as "to", distance from table;

[pavanigoud]

please comeup with more interview questions (sql) that would be helpful. Thank you

[ashwanikumarkaushik]

Sir, I enjoyed this session. Great explanation.
I learnt SQL from a course recommended by you in one of your videos. SQL Go from Zero to hero by Jose Portilla. Few concepts were not covered in that course, such as windows functions, greatest, least etc. Can you please tell where can I also learn such concepts?

[Shubhangisingh]

Sir, u have given 3 method bt we can simply write it as follows -
Select * from travel
Where source IN ( Mumbai, mathura, nagpur);

Plz tell me if it is correct?

[OmkarShinde-bzoy]

here we can use mod function mod(id, 2)=0 actully we can solve many methods but sir you solved very easy way great

[SatyaMishra-sv]

Hello, could you please help on min vs least, while doing least are we need partion on table ?