这个问题已经在这里有一个答案 :
可能重复:
如何消除TSQL NULL字段
我使用SSMS 2008 R2和正在开发一个TSQL查询。 我想只有1记录/ PROFILE_NAME。 因为一些值是NULL,我目前在做LEFT上大部分表的连接。 但与LEFT JOIN的问题是,现在我得到> 1点的记录对于一些profile_names!
但是,如果我改变了为内部连接,然后一些profile_names被完全排除,因为他们有这些列的NULL值。 如何限制查询结果只有一个记录/ PROFILE_NAME无论NULL值? 如果有非NULL值,那么我希望它选择与非NULL值的记录。 这里是初始查询:
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
from group_profile gp With (NoLock)
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
正如你所看到的,上面查询的结果是1行/ PROFILE_NAME:
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
但现在看,当我在2 LEFT JOIN的添加和1个附加列发生了什么:
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
from group_profile gp With (NoLock)
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 race_info ri with (nolock) on ri.race_info_id = race.race_info_id
上面的查询结果都一样profile_names的,但有些与NULL值的比赛:
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
不幸的是,复杂化,我需要在2个额外的表来参加这一个额外的字段值(种族)的事项。 如果我只是改变了过去两年LEFT JOIN的上方为内部连接,然后我消除上面的空行。 但我也消除一些profile_names的:
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
希望我提供了所有的,你需要为这个问题的细节。