使用 GROUP BY SQL 选择多列

Question

I am trying to select the min date value from one column, while grouping by another non-unique id column which has multiple duplicate values and also want to show the same rows that satisfy previous two conditions. The original database columns looks something like:

['TransactionDate','TransactionStatusID','DateOfEntry','DateOfService','Amount','TransactionTypeID','PaymentTypeId','PostDate','BillID','ChargeDetailID']

and 2nd table looks like:

['Amount', 'PracticeID', 'LoadDate', 'DateOfService', 'PerformingProvderID', 'CPTCodeID', 'ChargeDetailID']

I am joining these two tables on "ChargeDetailID" like:

SELECT  cd.PatientID, MIN(t.DateOfService) AS "Date Of Service"
FROM ChargeDetail as cd inner join transactions as t on cd.ChargeDetailID = t.ChargeDetailID
WHERE cd.PatientID IS NOT NULL
GROUP BY cd.PatientID   

Results that I get from this query:

|           PatientID|Date Of Service|
+--------------------+---------------+
|D37224C7-9157-4C5...|     2020-03-30|
|5E693AF8-8332-477...|     2014-01-07|
|8C071F5C-2210-4A6...|     2013-02-14|
|38B11DAE-3FF1-4AD...|     2012-03-14|
|7DB00C43-36F6-40E...|     2009-01-16|
|940EEC5C-4781-4EB...|     2016-12-08|

Results I want:

|           PatientID|Date Of Service|  cd.Amount| cd.BillID|
+--------------------+---------------+-----------+----------+
|D37224C7-9157-4C5...|     2020-03-30|   500     |10009
|5E693AF8-8332-477...|     2014-01-07|   250     |1492
|8C071F5C-2210-4A6...|     2013-02-14|  350      |15892
|38B11DAE-3FF1-4AD...|     2012-03-14|  222      |15596
|7DB00C43-36F6-40E...|     2009-01-16|  899      |20566
|940EEC5C-4781-4EB...|     2016-12-08|  650      |9566

Answer 1

You can use windows function as below-

Select 
    PatientID
  , Amount
  , BillId
  , DateOfService As "Date Of Service"
from
 (SELECT  
     cd.PatientID
    ,cd.Amount
    ,cd.BillId
    ,t.DateOfService
    ,row_number() over(partition by cd.PatientID order by t.DateOfService asc) as seqnum
FROM ChargeDetail as cd inner join transactions as t 
on cd.ChargeDetailID = t.ChargeDetailID
WHERE cd.PatientID IS NOT NULL) t
Where t.seqnum = 1;

Note the MySQL & SqlServer are 2 different databases however the above approach should work for both.

Answer 2

You can add cd.amount and cd.billid in the group by. But requirement isnt much clear. You can use window functions too.

SELECT  cd.PatientID, cd.Amount, cd.BillID, MIN(t.DateOfService) AS "Date Of Service"
FROM ChargeDetail as cd inner join transactions as t on cd.ChargeDetailID = t.ChargeDetailID
WHERE cd.PatientID IS NOT NULL
GROUP BY cd.PatientID , cd.Amount, cd.BillID