I have a simple task which I to be honest have no idea how to accomplish. I have these values from SQL query:
| DocumentNumber | CustomerID |
------------------------------
| AAA | 1 |
| BBB | 1 |
| CCC | 2 |
| DDD | 3 |
-------------------------------
I would like to display a bit modified table like this:
| DocumentNumber | CustomerID | Repeate |
-----------------------------------------
| AAA | 1 | Multiple |
| BBB | 1 | Multiple |
| CCC | 2 | Single |
| DDD | 3 | Single |
------------------------------------------
So, the idea is simple - I need to append a new column and set 'Multiple' and 'Single' value depending on if customer Id exists multiple times
Use window functions:
select t.*,
(case when count(*) over (partition by CustomerId) = 1 then 'Single'
else 'Multiple'
end) as repeate
from t;