How to eliminate NULL fields in TSQL

问题

I am developing a TSQL query for SQL Server 2008 R2. I am trying to develop this query to identify one record / client. Because some of these values are NULL, I am currently doing LEFT JOINS on most of the tables. But the problem with the LEFT JOINs is that now I get > 1 record for some clients.

But if I change this to INNER JOINs then some clients are excluded entirely because they have NULL values for these columns. How do I limit the query result to just one record / client regardless of NULL values? And if there are non-NULL values then I want it to choose the record with non-NULL values. Here is some of my current output:

group_profile_id    profile_name    license_number  is_accepting    is_accepting_placement  managing_office region  vendor_name vendor_id   applicant_type  Office Address  status_description  Cert Date2  race    ethnicity_desc  religion
9CD932F1-6BE1-4F80-AB81-0CE32C565BCF    Atreides Foster Home 1  Atreides1               1   Yes Manchester, NH  Gulf Atlantic   Atreides1   00000007                Treatment Foster Home   4042 Arrakis Avenue, Springfield, VT  05156 Open/Re-opened  2011-06-01 00:00:00.000 NULL    NULL    NULL
DCE354D5-A7CC-409F-B5A3-89BF664B7718    Averitte, Leon and Sandra   00000044                1   Yes Birmingham, AL  Gulf Atlantic   AL Averitte, Leon and Sandra    00000044                Treatment Foster Home   3816 5th Avenue, Bessemer, AL  35020, (205)482-4307 Open/Re-opened  2011-08-05 00:00:00.000 NULL    NULL    NULL
DCE354D5-A7CC-409F-B5A3-89BF664B7718    Averitte, Leon and Sandra   00000044                1   Yes Birmingham, AL  Gulf Atlantic   AL Averitte, Leon and Sandra    00000044                Treatment Foster Home   3816 5th Avenue, Bessemer, AL  35020, (205)482-4307 Open/Re-opened  2011-08-05 00:00:00.000 Caucasian/White Non Hispanic    NULL
AD02A43C-6F38-4F35-8C9E-E12422690BFB    Bass, Matthew and Sarah 00000076                1   Yes Jacks    on, MS Central Gulf Coast  MS Bass, Matthew and Sarah  00000076                Treatment Foster Home   506 Eagelwood Drive, Florence, MS  39073, (601)665-7169 Open/Re-opened  2011-04-01 00:00:00.000 NULL    NULL    NULL
AD02A43C-6F38-4F35-8C9E-E12422690BFB    Bass, Matthew and Sarah 00000076                1   Yes Jackson, MS Central Gulf Coast  MS Bass, Matthew and Sarah  00000076                Treatment Foster Home   506 Eagelwood Drive, Florence, MS  39073, (601)665-7169 Open/Re-opened  2011-04-01 00:00:00.000 Caucasian/White NULL    Baptist

You can see that both Averitte and Bass profile names have one record with NULL race, ethnicity, religion. How do I eliminate these rows (rows 2 and 4)?

Here is my query currently:

select distinct
        gp.group_profile_id,
        gp.profile_name,
        gp.license_number,
        gp.is_accepting,
        case when gp.is_accepting = 1 then 'Yes'
             when gp.is_accepting = 0 then 'No '
                        end as is_accepting_placement,
        mo.profile_name as managing_office,
        regions.[region_description] as region,     
        pv.vendor_name,
        pv.id as vendor_id,
        at.description as applicant_type,
        dbo.GetGroupAddress(gp.group_profile_id, null, 0) as [Office Address],
        gsv.status_description,
        ri.[description] as race,
        ethnicity.description as ethnicity_desc,
        religion.description as religion
from  group_profile gp With (NoLock)
    --Office Information
        inner join group_profile_type gpt With (NoLock) on gp.group_profile_type_id = gpt.group_profile_type_id and
                    gpt.type_code = 'FOSTERHOME' and gp.agency_id = @agency_id and gp.is_deleted = 0
        inner join group_profile mo With (NoLock) on gp.managing_office_id = mo.group_profile_id
        left outer join payor_vendor pv With (NoLock) on gp.payor_vendor_id = pv.payor_vendor_id
        left outer join applicant_type at With (NoLock) on gp.applicant_type_id = at.applicant_type_id and at.is_foster_home = 1
        inner join group_status_view gsv With (NoLock) on gp.group_profile_id = gsv.group_profile_id and gsv.status_value = 'OPEN' and gsv.effective_date =  
                            (Select max(b.effective_date) from  group_status_view b  With (NoLock)
                            where gp.group_profile_id = b.group_profile_id)
        left outer join regions With (NoLock) on isnull(mo.regions_id, gp.regions_id) = regions.regions_id
left join enrollment en on en.group_profile_id = gp.group_profile_id
        join event_log el on el.event_log_id = en.event_log_id
    left join people client on client.people_id = el.people_id
    left join   race With (NoLock) on el.people_id = race.people_id
    left join group_profile_race gpr with (nolock) on gpr.race_info_id = race.race_info_id
    left join race_info ri with (nolock) on ri.race_info_id = gpr.race_info_id
    left join ethnicity With(NoLock) On client.ethnicity = ethnicity.ethnicity_id
    left join religion on client.religion = religion.religion_id

回答1:

Try grouping by group_profile_id and selecting MAX() of every other column. MAX will select the non-null value (if one exists, or the maximum if multiple exist) of each repeating entry. Although the more efficient solution would involve sorting out additional NULL rows in the data, from first glance.

来源：https://stackoverflow.com/questions/11164232/how-to-eliminate-null-fields-in-tsql