如何在PostgreSQL

Question

陣列分成數行運行此查詢：

SELECT id,selected_placements 
    FROM app_data.content_cards 

我得到一個表是這樣的：

+----+-------------------------------+ 
| id | selected_placements   | 
+----+-------------------------------+ 
| 90 | {162,108,156,80,163,155,NULL} | 
+----+-------------------------------+ 
| 91 | {}       | 
+----+-------------------------------+ 

我現在要做的就是讓這相同的信息，但陣列分割成行，所以我得到這樣的結果：

+----+---------------------+ 
| id | selected_placements | 
+----+---------------------+ 
| 90 | 162     | 
+----+---------------------+ 
| 90 | 108     | 
+----+---------------------+ 
| 90 | 156     | 
+----+---------------------+ 
| 90 | 80     | 
+----+---------------------+ 
| 90 | 163     | 
+----+---------------------+ 
| 90 | 155     | 
+----+---------------------+ 

正如你所看到的，我不想讓「seleclec」 ted_placements」。

我正在使用PostgreSQL 8.0.2。

非常感謝！

Answer 1

我建議你升級你的Postgres版本。所有受支持版本支持unnest()：

SELECT x.* 
FROM (SELECT id, UNNEST(selected_placements) as selected_placement 
     FROM app_data.content_cards 
    ) x 
WHERE selected_placement IS NOT NULL; 

在早期版本中，你可以努力挑選出來一次一個。以下是測試和工程，儘管在9.5：

with content_cards as (
    select 1 as id, array['a', 'b', 'c'] as selected_placements 
    ) 
SELECT id, selected_placements[num] as selected_placement 
FROM (SELECT cc.*, generate_series(1, ccup.maxup) as num 
     FROM content_cards cc CROSS JOIN 
      (SELECT MAX(ARRAY_UPPER(cc.selected_placements, 1)) as maxup 
      FROM content_cards cc 
      ) ccup 
    ) x 
WHERE selected_placements[num] IS NOT NULL;