sql oracle - remove duplicate value

问题

I have the below query, it returns the column UP that contents duplicated values (for example '111' exists 5 times but not all of them have a value in CODE_DEPT)

select  UP, CODE_DEPT from ESP_ENSEIGNANT;

UP    CODE_DEPT
111     f
555
111
222     y
222
111
444
666
222
444     k
111     f
111     
666     x

so i want to update my query to get a unique UP with CODE_DEPT (if CODE_DEPT is not empty it returns else it returns empty)

UP    CODE_DEPT
111     f
555
222     y
444     k
666     x

回答1:

You can use aggregation:

select up, max(code_dept) as code_dept
from ESP_ENSEIGNANT ee
group by up;

来源：https://stackoverflow.com/questions/65708761/sql-oracle-remove-duplicate-value