Question

I’m trying to make a query with postgresql.
The database contains two relations: “kingdom”, which includes some english kings, and “dinasty”, which contains some people from the stuart dinasty

The relation “kingdom” includes the king name and when his kingdom started and ended. The relation “dinasty” includes name, gender, birth and death.

What I’m trying to query is the king that was the oldest one when he died.

With my query I’m receiving this error at LINE 3 (NOT IN): subquery has too many columns

This is the query:

SELECT kingdom.king, dinasty.birth, dinasty.death
FROM kingdom, dinasty
WHERE kingdom.king = dinasty.name AND kingdom.king NOT IN
(
    SELECT DISTINCT R1.king, R1.birth, R1.death
    FROM
    (
        SELECT DISTINCT R1.king, D1.birth, D1.death
        FROM kingdom AS R1, dinasty AS D1, dinasty AS D2
        WHERE R1.king=D1.name
    ) AS R1, 
    (
        SELECT DISTINCT R1.king, D1.birth, D1.death
        FROM kingdom AS R1, dinasty AS D1, dinasty AS D2
        WHERE R1.king=D1.name
    ) AS R2
    WHERE R1.death-R1.birth < R2.death-R2.birth
);

What is inside the NOT IN is correct.

Answer 1

You are projecting three columns in your subquery, but comparing a single one of them in the IN clause. Select just the required column (r1.king) for the IN in the subquery:

SELECT kingdom.king, dinasty.birth, dinasty.death
FROM kingdom, dinasty
WHERE kingdom.king = dinasty.name AND kingdom.king NOT IN
(
    SELECT DISTINCT R1.king
    FROM
    (
        SELECT DISTINCT R1.king, D1.birth, D1.death
        FROM kingdom AS R1, dinasty AS D1, dinasty AS D2
        WHERE R1.king=D1.name
    ) AS R1, 
    (
        SELECT DISTINCT R1.king, D1.birth, D1.death
        FROM kingdom AS R1, dinasty AS D1, dinasty AS D2
        WHERE R1.king=D1.name
    ) AS R2
    WHERE R1.death-R1.birth < R2.death-R2.birth
);