Question

I have a table with data:

id  a_no  accountname
1    NULL   ac1  
1    234    ac2
1    567    ac3
2    NULL   ac4

I want to select row with the following criteria:

1. if same id exist in more than 1 row, then remove the row with a_no=NULL
2. if id exist in 1 row only, keep that row unchanged

So that the resulting rows should be

id  a_no  accountname
1    234    ac2
1    567    ac3
2    NULL   ac4

How to write the T-SQL query? Thanks.

Answer 1

select * from yourtable
where a_no is not null
union all
select * from yourtable
where id not in 
    (select id from your table where a_no is not null)