將重複值移動到另一列

Question

我有一個基於列id_location的條目對的表。

"id_image", "score", "stddev", "id_image2", "score2", "stddev2", "id_location" 
3484,  0.90422, 0.06476, NULL,  NULL,  NULL,  13 
18,   0.71598, 0.06101, NULL,  NULL,  NULL,  13 

如果我想合併重複的id_location並將其移動到不同的列，因此每一行都是獨一無二的，我會怎麼做呢？

我看着轉置和支點，但那些看起來有些不同。

這將是結果表：

"id_image", "score", "stddev", "id_image2", "score2", "stddev2", "id_location" 
3484,  0.90422, 0.06476, 18,   0.71598, 0.06101, 13 

Answer 1

這將做到這一點，具有較高id_image出現在第一槽：

INSERT INTO new_table 
SELECT t1.id_image, t1.score, t1.stddev, t2.id_image, 
    t2.score, t2.stddev, t1.id_location 
FROM old_table t1 
JOIN old_table t2 
ON t2.id_location = t1.id_location 
    AND t2.id_image < t1.id_image 

Answer 2

也許使用子查詢：

UPDATE your_table 
SET 
    score2 = (SELECT score FROM your_table WHERE id_image = 3484), 
    stddev2 = (SELECT stddev FROM your_table WHERE id_image = 3484), 
WHERE id_image = 18;