Ways of Replacing null values in Sql Server with customize value.

Select person_id,IsNull(Middle_Name,'NA') as name from person_master where MIDDLE_NAME is null;

Select person_id,Coalesce(Middle_name,'NA') as name from person_master where MIDDLE_NAME is null;

Select p.person_id,case when p.MIDDLE_NAME is null then 'NA' else p.MIDDLE_NAME end as name from person_master p where p.MIDDLE_NAME is null;