How to update corresponding records as exactly same based on other column

Question

Hi,

I am using below sql to update Effective_Start_Date as same as updated_date for each source_id.But i am not not able to get it.

Here i have Source_Id having duplicates with different Updated_date

WITH CTE AS (

SELECT *, ROW_NUMBER() OVER (PARTITION BY Source_Id order by Updated_date ) As rn

from Declaration_Backup]

where Effective_Start_Date IS NULL

)

Update CTE

SET Effective_Start_Date = Updated_date

Sample data:

Need to change as below

Please suggest how to chnage sql.

Please suggest how to chnage sql.

Answer 1

Maybe I don't understand the problem, but isn't it just:

Update Declaration_Backup
SET Effective_Start_Date = Updated_date
where Effective_Start_Date IS NULL