Solvesql Solution

- SQL

Author: SubAkBa

Solvesql/Solutions/artists-without-artworks.sql

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+-- @ss.idx: 5
+-- @ss.level: 3
+-- @ss.title: 작품이 없는 작가 찾기
+-- @ss.slug: artists-without-artworks
+-- @ss.category: JOIN/UNION
+-- @ss.note:
+
+SELECT ar.artist_id
+     , ar.name
+FROM artists ar
+WHERE ar.death_year IS NOT NULL
+AND NOT EXISTS (
+    SELECT 1
+    FROM artworks a
+    JOIN artworks_artists aa ON a.artwork_id = aa.artwork_id
+    WHERE aa.artist_id = ar.artist_id
+);

Solvesql/Solutions/mentor-mentee-list.sql

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+-- @ss.idx: 6
+-- @ss.level: 3
+-- @ss.title: 멘토링 짝꿍 리스트
+-- @ss.slug: mentor-mentee-list
+-- @ss.category: JOIN/UNION
+-- @ss.note:
+
+SELECT
+    e1.employee_id AS mentee_id,
+    e1.name        AS mentee_name,
+    e2.employee_id AS mentor_id,
+    e2.name        AS mentor_name
+FROM employees e1
+LEFT JOIN employees e2 ON e2.department != e1.department
+    AND e2.join_date <= DATE_SUB('2021-12-31', INTERVAL 2 YEAR)
+WHERE e1.join_date >= DATE_SUB('2021-12-31', INTERVAL 3 MONTH)
+ORDER BY mentee_id, mentor_id;