SQL Join Types and Example | Dataford Interview Questions

What is the difference between an inner join, a left outer join, and a cross join? Write a query to demonstrate.

Use the employees and departments tables. Return one summary row for each join type and make the difference in result cardinality clear.

Output

Columns: join_type, result_rows, and unmatched_left_rows
One row for each join type, ordered as INNER JOIN, LEFT OUTER JOIN, then CROSS JOIN
For CROSS JOIN, report 0 unmatched left rows because no matching condition is evaluated

employees

Column	Type	Description
employee_idPK	INTEGER	Unique employee identifier
employee_name	VARCHAR(100)	Employee's full name
department_id	INTEGER	Referenced department identifier, when assigned

departments

Column	Type	Description
department_idPK	INTEGER	Unique department identifier
department_name	VARCHAR(100)	Department name

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