如何选择一个字段不同的单行？ 数据库服务器

Question

I have a table like below:

ID            NAME          SCHOOL          GRADUATIONYEAR           DEGREE                MAJOR
--------------------------------------------------------------------------------------------------
100           Ben         University1          2015             Bachelor of Arts           Major1
100           Ben         University1          2015             Bachelor of Arts           Major2
100           Ben         University2          2017             Master of Science          Major3

Since Ben has two records that are from the same university due to double majors (as you can see same School, graduation year, and degree), I only want to pull one of those records rather than both of those records, it doesn't matter which Major I pull, just has to be one instead of both of those records. So ideally, I'd like for it to be like below:

ID            NAME          SCHOOL          GRADUATIONYEAR           DEGREE                MAJOR
--------------------------------------------------------------------------------------------------
100           Ben         University1          2015             Bachelor of Arts           Major1
100           Ben         University2          2017             Master of Science          Major3

I have tried to do a delete like below, but this ends up deleting all of the records, is it possible to maybe use CASE in this scenario?

DELETE FROM #table1 
WHERE ID = ID AND NAME = NAME AND SCHOOL = SCHOOL AND DEGREE = DEGREE

Answer 1

Use row_number() :

select *
from (
    select
        t.*,
        row_number() over(
            partition by name, school, graduationyear, degree 
            order by major
        ) rn
    from mytable t
) t
where rn = 1

When two rows have the same ame, school, graduation year and degree, the query retains the one with the smallest major , alphabetically-wise (you can change the order by clause of row_number() if you want another criteria).

If you wanted a delete statement:

with cte as (
    select row_number() over(
        partition by name, school, graduationyear, degree 
        order by major
    ) rn
    from mytable 
)
delete from cte where rn > 1