SQL: Parents With Siblings | Dataford Interview Questions

Janus Henderson Investors maintains employee family relationships in a student and parent registry. Write a PostgreSQL query to list only parents associated with at least two distinct students, treating those students as siblings.

Requirements

Join parent, student_parent, and student.
Return the parent ID, parent name, and number of distinct associated students.
Include only parents with at least two distinct students.
Sort the results by parent_id ascending.

Schema

parent

Column	Type	Description
parent_idPK	INT	Unique parent identifier
parent_name	VARCHAR(100)	Parent's full name
email	VARCHAR(255)	Parent email address

student

Column	Type	Description
student_idPK	INT	Unique student identifier
student_name	VARCHAR(100)	Student's full name

student_parent

Column	Type	Description
student_idPK	INT	Student identifier in the relationship
parent_idPK	INT	Parent identifier in the relationship
relationship_type	VARCHAR(30)	Relationship classification

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