Postgres 14

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select version();


version


PostgreSQL 14.5 on x86_64-pc-linux-gnu, compiled by gcc (GCC) 8.5.0 20210514 (Red Hat 8.5.0-10), 64-bit


create table t (
id int,
num_a int,
num_b int
);

insert into t values
(1,	1,	168),

-- (2,	1,	7),
-- (2,	1,	5),
(2,	1,	4),

(2,	5,	24),
(2,	6,	24),
(3,	1,	36);
5 rows affected

WITH t_rn AS (
    SELECT *, ROW_NUMBER() OVER (PARTITION BY id ORDER BY num_b) AS rn FROM t
),
least_common_multiple AS (
    WITH RECURSIVE least_multiples AS (
        SELECT 
            id,
            num_b,
            num_b AS lm,
            rn
        FROM t_rn
        WHERE rn = 1
        UNION ALL
        SELECT 
            t_rn.id, 
            t_rn.num_b,
            LCM(t_rn.num_b, lm.lm),
            t_rn.rn
        FROM t_rn
        JOIN least_multiples lm ON lm.id = t_rn.id AND t_rn.rn = lm.rn + 1
    )
    SELECT 
        id,
        MAX(lm) AS lcm
    FROM least_multiples
    GROUP BY id
)
SELECT 
    t.*,
    SUM(t.num_a * lm.lcm / t.num_b) OVER (PARTITION BY t.id) AS suma,
    lm.lcm AS denom_b
FROM t
JOIN least_common_multiple lm ON t.id = lm.id


id
num_a
num_b
suma
denom_b


1
1
168
1
168

2
1
4
17
24

2
5
24
17
24

2
6
24
17
24

3
1
36
1
36