如何添加标记每个值之一的列？

Question

我在 SQL 中加入两个表。我目前的 SQL 为：

SELECT table1.ProjectName AS "Project Name",
  table1.ProjectCost AS "Project Cost",
  table2.ExpenseName AS "Expense Name",
  table2.ExpenseCost AS "Expense Cost"
  FROM TABLE1 table1
  INNER JOIN TABLE2 table2
  ON table1.ProjectName = table2.ProjectName;

结果如下：

Project Name    | Project Cost  | Expense Name  | Expense Cost
------------------------------------------------------------
Project 1   | 123456        | Labor     | 12365  
Project 1   | 123456        | Rent      | 120000  
Project 2   | 8421              | (null)    | (null)  
Project 3   | 987654        | Paper     | 1023  
Project 3   | 987654        | Pens      | 546  

我想添加一行来标记每个项目名称之一，以便我可以在 Tableau 中对其进行过滤并汇总项目成本。

前：

Project Name    | Project Cost  | Expense Name  | Expense Cost  | Unique Value
----------------------------------------------------------------------------
Project 1   | 123456        | Labor     | 12365     | Y  
Project 1   | 123456        | Rent      | 12000     | N  
Project 2   | 8421      | (null)    | (null)        | Y  
Project 3   | 987654        | Paper     | 1023      | Y  
Project 3   | 987654        | Pens      | 546       | N  
Project 3   | 987654        | Party     | 9856      | N

Answer 1

我想你可以使用滞后功能，其实我不久前就问过这个问题，我可以分享我的问题，也许它可以帮助你。但是，您可以创建一个临时表并根据滞后函数填充该列，而不是选择该值：

SELECT Only one value per ID - SQL Server

Answer 2

你也可以使用排名：

select t.* 
     , case when lag(project_name) over (partition by 1 order by project_name, rownum) = project_name then 'N' else 'Y' end n
     , case when rank() over (partition by project_name order by rownum) >  1 then 'N' else 'Y' end n
from join_result