SQL在一行中选择第一个值，然后将该值插入另一列

Question

我对sql不是很好，所以我不确定这是否可行。 或者甚至在excel？ 我正在尝试选择第一个值并忽略Product_ID中的重复项，然后将该行的第一个值添加到Title列。

另请注意，我的产品列表超过25,000件商品。

所以拿这个：

+---------------+------------+-------+-------------+-------+
| Product_Count | Product_ID | Title | _Color_Name | _Size |
+---------------+------------+-------+-------------+-------+
| 2             | 14589      |       | Black       | 00    |
| 3             | 14589      |       | Black       | 0     |
| 4             | 14589      |       | Black       | 2     |
| 5             | 14589      |       | Black       | 4     |
| 6             | 14589      |       | Black       | 6     |
| 11            | 14589      |       | Dark Coral  | 00    |
| 12            | 14589      |       | Dark Coral  | 0     |
| 13            | 14589      |       | Dark Coral  | 2     |
| 14            | 14589      |       | Dark Coral  | 4     |
| 15            | 14589      |       | Dark Coral  | 6     |
| 129           | 15027      |       | Aqua        | 00    |
| 130           | 15027      |       | Aqua        | 0     |
| 131           | 15027      |       | Aqua        | 2     |
| 132           | 15027      |       | Aqua        | 4     |
| 133           | 15027      |       | Aqua        | 6     |
| 138           | 15027      |       | Black       | 00    |
| 139           | 15027      |       | Black       | 0     |
| 140           | 15027      |       | Black       | 2     |
| 141           | 15027      |       | Black       | 4     |
| 142           | 15027      |       | Black       | 6     |
+---------------+------------+-------+-------------+-------+

把它变成这个：

+---------------+------------+-------+-------------+-------+
| Product_Count | Product_ID | Title | _Color_Name | _Size |
+---------------+------------+-------+-------------+-------+
| 2             | 14589      | 14589 | Black       | 00    |
| 3             | 14589      |       | Black       | 0     |
| 4             | 14589      |       | Black       | 2     |
| 5             | 14589      |       | Black       | 4     |
| 6             | 14589      |       | Black       | 6     |
| 11            | 14589      |       | Dark Coral  | 00    |
| 12            | 14589      |       | Dark Coral  | 0     |
| 13            | 14589      |       | Dark Coral  | 2     |
| 14            | 14589      |       | Dark Coral  | 4     |
| 15            | 14589      |       | Dark Coral  | 6     |
| 129           | 15027      | 15027 | Aqua        | 00    |
| 130           | 15027      |       | Aqua        | 0     |
| 131           | 15027      |       | Aqua        | 2     |
| 132           | 15027      |       | Aqua        | 4     |
| 133           | 15027      |       | Aqua        | 6     |
| 138           | 15027      |       | Black       | 00    |
| 139           | 15027      |       | Black       | 0     |
| 140           | 15027      |       | Black       | 2     |
| 141           | 15027      |       | Black       | 4     |
| 142           | 15027      |       | Black       | 6     |
+---------------+------------+-------+-------------+-------+

Answer 1

您可以使用PARTITION窗口化ProductIds ，然后使用ROW_NUMBER()标识每个分区中的第一行：

SELECT 
  ProductID, 
  Product_Count, 
  CASE WHEN rn = 1 THEN ProductID else null END AS Title, 
  Color_Name, 
  Size
FROM
(
    SELECT ProductID, Product_Count, Color_Name, Size,
    ROW_NUMBER() OVER (PARTITION BY ProductID ORDER BY Product_Count) AS rn
    FROM product_stock
) AS X;

SqlFiddle在这里

Answer 2

试试这个，

Declare @t table (col1 int,col2 int,col3 int)
insert into @t values(2,3,null),(2,4,null),(5,3,null),(5,4,null)

;with CTE as
(select *,ROW_NUMBER()over(partition by col1 order by col1)rn from @t

)

select a.col1,a.col2,case when a.rn=1 then b.col1 end col3 from CTE a
left join (select col1 from cte where rn>1) b on a.col1=b.col1

Answer 3

使用UNIQUE创建表。

CREATE TABLE recentDetails"
                    + "(_id integer primary key autoincrement,"
                    + "fileName TEXT, filePath TEXT UNIQUE ,fileSize TEXT,fileDate TEXT);

Answer 4

SELECT * from TABLE_NAME WHERE Product_count IN (SELECT MIN(Product_COUNT) FROM TABLE_NAME where Product_ID IN (SELECT DISTINCT Product_ID FROM TABLE_NAME)) AND Product_ID IN (SELECT DISTINCT Product_ID FROM TABLE_NAME)