How do I add a column that marks one of each value? - sql

Question

I'm joining two tables in SQL. I currently have the SQL as:
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;
The result looks like:
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
I want to add a row that marks one of each Project Name so that I can filter over it in Tableau and sum the projects costs.
EX:
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

I suposse you can use the lag function, I actually asked this not a long time ago, I can share my question, maybe it helps you. But instead of selecting the value you could create a table temporal table and populate that column based on the lag function:
SELECT Only one value per ID - SQL Server

Answer 2

You can use rank as well:
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