Find Shared Names Pairs

MediumSQL · PostgreSQL00:00

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Your question is Find Shared Names Pairs. Start with the requirements and the two tables on the right.

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Problem

Given two tables (User_age and user_names), find all pairs of userids sharing the same name, returning userid_1, userid_2, and name without duplicates (excluding reverse pairs).

Asked in the SQL and coding round stage. A commenter separately confirmed Meta asks this same question in Solutions Architect interviews.

Output

Return one row per unordered pair of users represented in both tables.
Columns must be userid_1, userid_2, and name.
Exclude rows where name is NULL, and ensure userid_1 is less than userid_2.
Order by name, userid_1, and userid_2 ascending.

Schema

User_age

Column	Type	Description
useridPK	INTEGER	Unique user identifier
age	INTEGER	User age, when available

user_names

Column	Type	Description
useridPK	INTEGER	User identifier referencing User_age
name	VARCHAR(100)	User display name

TablesUser_ageuser_names

Your solutionPostgreSQL

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