StackOverflow question #47440855, PostgreSQL

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CREATE TABLE work_units (id INT);
    CREATE TABLE work_units_skills (work_unit_id INT, skill_id INT);
    CREATE TABLE workers_skills (worker_id INT, skill_id INT);

INSERT INTO work_units (id) VALUES (1);
    INSERT INTO work_units (id) VALUES (2);
    INSERT INTO work_units (id) VALUES (3);
    INSERT INTO work_units (id) VALUES (4);
    INSERT INTO work_units (id) VALUES (5);

INSERT INTO work_units_skills (work_unit_id, skill_id) VALUES (1, 1);
    INSERT INTO work_units_skills (work_unit_id, skill_id) VALUES (1, 2);
    INSERT INTO work_units_skills (work_unit_id, skill_id) VALUES (1, 3);
    INSERT INTO work_units_skills (work_unit_id, skill_id) VALUES (2, 3);
    INSERT INTO work_units_skills (work_unit_id, skill_id) VALUES (2, 4);
    INSERT INTO work_units_skills (work_unit_id, skill_id) VALUES (2, 5);
    INSERT INTO work_units_skills (work_unit_id, skill_id) VALUES (3, 3);

INSERT INTO workers_skills (worker_id, skill_id) VALUES (1, 1);
    INSERT INTO workers_skills (worker_id, skill_id) VALUES (1, 3);
    INSERT INTO workers_skills (worker_id, skill_id) VALUES (1, 5);
    INSERT INTO workers_skills (worker_id, skill_id) VALUES (2, 3);
    INSERT INTO workers_skills (worker_id, skill_id) VALUES (2, 5);
    INSERT INTO workers_skills (worker_id, skill_id) VALUES (3, 5);
    INSERT INTO workers_skills (worker_id, skill_id) VALUES (5, 1);

SELECT work_units.*
    FROM work_units
    -- some joins
    WHERE NOT EXISTS (
            SELECT skill_id
            FROM work_units_skills
            WHERE work_unit_id = work_units.id

EXCEPT

SELECT skill_id
            FROM workers_skills
            WHERE worker_id = 1 -- the worker id that made the request
          )
    -- AND a bunch of other conditions
    -- ORDER BY something complex
    FOR UPDATE SKIP LOCKED;

SELECT work_units.*
    FROM work_units
    -- some joins
    WHERE NOT EXISTS (
            SELECT skill_id
            FROM work_units_skills wus
            WHERE work_unit_id = work_units.id
            AND NOT EXISTS (
                SELECT skill_id
                FROM workers_skills ws
                WHERE worker_id = 1 -- the worker id that made the request
                  AND ws.skill_id = wus.skill_id
            )
          )
    -- AND a bunch of other conditions
    -- ORDER BY something complex
    FOR UPDATE SKIP LOCKED;


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