Test_Sportmaster

/*create table tab(
  week_end VARCHAR(30),
  category VARCHAR(30),
  out_of_stock FLOAT,
  delivery_lag FLOAT,
  product_deficit FLOAT,
  nostock FLOAT,
  other FLOAT);
INSERT INTO tab VALUES ('23.01.2022', 'Equipment', 0.24, 0.02, 0.04, 0.07, 0.11),
('23.01.2022', 'Shoes', 0.14, 0.04, 0.04, 0.03, 0.03),
('23.01.2022', 'Clothing', 0.16, 0.03, 0.05, 0.06, 0.02);*/
WITH t3 AS (
    SELECT t1.week_end, t1.category, t1.out_of_stock, t2.*
    FROM tab AS t1
        cross join lateral (
             VALUES
             (t1.delivery_lag, 'delivery_lag'),
             (t1.product_deficit, 'product_deficit'),
             (t1.nostock, 'nostock'),
             (t1.other, 'other')
        ) AS t2(d, cause1)
),
t4 AS (
    SELECT *, DENSE_RANK() OVER(PARTITION BY category ORDER BY d DESC) AS r
    FROM t3
),
t5 AS (
    SELECT *
    FROM t4
    WHERE r=1
),
t6 AS (
  SELECT week_end, category, out_of_stock, cause1||' ('||d||')' AS cause2
  FROM t5
)
SELECT week_end, category, out_of_stock, STRING_AGG(cause2, ', ') AS cause
FROM t6
GROUP BY week_end, category, out_of_stock