Question

我有两张桌子：patient_allergens

prob_person_id  allergens
--------------  ---------
123             NO KNOWN ALLERGIES

和patient_medication

med_person_id   med_start_date  medication_name
-------------   --------------  ---------------
123             20140819        Seroquel 50 mg tablet
123             20140819        trazodone 50 mg tablet
123             20140825        clonazepam 2 mg tablet
123             20150407        duloxetine 60 mg capsule,delayed release
123             20160222        atorvastatin 40 mg tablet

当我加入桌子时，我得到了：

select pa.prob_person_id, 
       pa.allergens, 
       pm.med_person_id, 
       pm.med_start_date, 
       pm.medication_name 
from patient_allergens pa 
left join patient_medication pm on pa.prob_person_id = pm.med_person_id                 


prob_person_id  allergens            med_person_id                          start_date  medication_name
--------------  ---------            -------------                          ----------  ---------------
123             NO KNOWN ALLERGIES  AF469E7B-3115-4715-8561-8088192D8AEE    20140819    Seroquel 50 mg tablet
123             NO KNOWN ALLERGIES  AF469E7B-3115-4715-8561-8088192D8AEE    20140819    trazodone 50 mg tablet
123             NO KNOWN ALLERGIES  AF469E7B-3115-4715-8561-8088192D8AEE    20140825    clonazepam 2 mg tablet
123             NO KNOWN ALLERGIES  AF469E7B-3115-4715-8561-8088192D8AEE    20150407    duloxetine 60 mg capsule,delayed release
123             NO KNOWN ALLERGIES  AF469E7B-3115-4715-8561-8088192D8AEE    20160222    atorvastatin 40 mg tablet

我不确定如何修改连接以获得具有NULL

的以下结果集

prob_person_id  allergens           med_person_id                           start_date  medication_name
--------------  ---------           -------------                           ----------  ---------------
123             NO KNOWN ALLERGIES  AF469E7B-3115-4715-8561-8088192D8AEE    20140819    Seroquel 50 mg tablet
NULL            NULL                NULL                                    20140819    trazodone 50 mg tablet
NULL            NULL                NULL                                    20140825    clonazepam 2 mg tablet
NULL            NULL                NULL                                    20150407    duloxetine 60 mg capsule,delayed release
NULL            NULL                NULL                                    20160222    atorvastatin 40 mg tablet

Answer 1

您可以使用Rank()来实现此目标。

--Setup test data
DECLARE @alergen TABLE (Name VARCHAR(16))
DECLARE @med TABLE (Name VARCHAR(16))

INSERT INTO @alergen
SELECT 'peanuts'

INSERT INTO @med 
SELECT 'acetomenophene'
UNION
SELECT 'ibuprofen'


--Show how rank will assign a row number to each record
SELECT RANK() OVER (ORDER BY name)
    , Name
FROM @alergen

SELECT RANK() OVER (ORDER BY name)
    , Name
FROM @med


--Combine the ranking queries to get the desired result
SELECT *
FROM (
    SELECT RANK() OVER (ORDER BY name) AS 'row_number'
        , Name
    FROM @alergen

) alergens
-- Use FULL JOIN so that all records are included even if there are row_numbers in one list that aren't in the other
FULL JOIN (
    SELECT RANK() OVER (ORDER BY name) AS 'row_number'
        , Name
    FROM @med
) meds ON alergens.row_number = meds.row_number

连接2个表时删除重复的行

1 个答案: