Explain different types of joins and their outputs.

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Accepted Answer

Joins in SQL combine data from multiple tables based on related columns, affecting the output based on join type.

INNER JOIN: Returns records with matching values in both tables. Example: SELECT * FROM Patients INNER JOIN Appointments ON Patients.ID = Appointments.PatientID.
LEFT JOIN: Returns all records from the left table and matched records from the right table. Example: SELECT * FROM Patients LEFT JOIN Appointments ON Patients.ID = Appointments.PatientID.
RIGHT JOIN: Returns all records from the right table and matched records from the left table. Example: SELECT * FROM Appointments RIGHT JOIN Patients ON Patients.ID = Appointments.PatientID.
FULL OUTER JOIN: Returns records when there is a match in either left or right table. Example: SELECT * FROM Patients FULL OUTER JOIN Appointments ON Patients.ID = Appointments.PatientID.
CROSS JOIN: Returns the Cartesian product of both tables. Example: SELECT * FROM Patients CROSS JOIN Appointments.