Day 22 of My Data Analytics Journey !

Today I explored SQL Joins – one of the most important concepts in relational databases and also practiced with some coding problems on HackerRank.

Types of Joins

INNER JOIN → Returns only the matching rows from both tables.

LEFT JOIN → …


This content originally appeared on DEV Community and was authored by Ramya .C

Today I explored SQL Joins – one of the most important concepts in relational databases and also practiced with some coding problems on HackerRank.

Types of Joins

  1. INNER JOIN → Returns only the matching rows from both tables.
  2. LEFT JOIN → Returns all rows from the left table + matched rows from the right table.
  3. RIGHT JOIN → Returns all rows from the right table + matched rows from the left table.
  4. FULL JOIN (or OUTER JOIN) → Returns all rows when there is a match in one of the tables.

Among these, the most commonly used is the INNER JOIN.

✅ INNER JOIN Example

Let’s say we have two tables:

movies

movie_id movie_name
1 Ghajini
2 Singam
3 Kaakha Kaakha

actors

actor_id actor_name
1 Surya
2 Asin
3 Jyothika

movie_actors

movie_id actor_id
1 1
1 2
3 1
3 3

📝 Query (INNER JOIN) 

SELECT m.movie_name, a.actor_name
FROM movies m
INNER JOIN movie_actors ma ON m.movie_id = ma.movie_id
INNER JOIN actors a ON ma.actor_id = a.actor_id;

Output

movie_name actor_name
Ghajini Surya
Ghajini Asin
Kaakha Kaakha Surya
Kaakha Kaakha Jyothika


This content originally appeared on DEV Community and was authored by Ramya .C


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