C# Windows Application Support By Ratnesh

Join (Join In SQL)

In SQL, a JOIN is used to combine data from two or more tables based on a related column between them.Simple Definition
👉 JOIN connects tables using a common field (like an ID) so you can get related data in one result.Example (Simple)

e.g. (Query)
SELECT doctor_name, company_name
FROM doctors
JOIN companies
ON doctors.company_id = companies.company_id;

✅ Result:

Dr. A | ABC Pharma

Why JOIN is Used
To fetch related data from multiple tables
To avoid data duplication
To maintain database normalization

Common Types of JOIN

INNER JOIN :Returns only matching records from both tables.
LEFT JOIN : Returns all records from the left table, even if no match exists.
RIGHT JOIN : Returns all records from the right table.
FULL JOIN : Returns all records from both tables.