Checking if ID exists and also if another column is null and updating another column - sql

Question

I am about to implement an update statement on a table. I know it sounds really simple, but I'm not able to get through it logically.
Scenario:
There is a table I have with the below format, that gets data everyday through a process. The columns on the table are as follows:
PKID | RecordID | ThirdPartyID | Action | DATEADDED
PKID: The auto incremental Primary Key.
RecordID: Can have duplicates.
ThirdpartyID: Can be multiple values and also accepts NULLS.
Action: The column that needs to be updated
DateAdded: Contains the GETDATE() of when the record is imported into the table.
Problem:
There is a process that imports new records into this table everyday. When the records are inserted for a day, I need to check the following:
Check if the newly Inserted RecordIDs are already existing in the table.
If the RecordID entered today, is already there in the table (there can be multiple entries of the same RecordID in the old records),
Check if the ThirdPartyID is NULL in the old records for that RecordID.
If the ThirdPartyID exists in any of the old records for that RecordID, update the Action Column with 'Multiple Entries.'
Else do nothing.
Please let me know if I can provide any further clarification or details in this regard.

Answer 1

I would approach the problem like this:
Load new data into a Temp table.
Inner Join the 2 tables on RecordID which will join only if the RecordID exists in both tables...
update the Action column to "Multiple Entries" if the ThirdPartyID field is also null.
Script should be something like this:
UPDATE Main
SET Action = 'Multiple Entries'
FROM Main INNER JOIN Temp ON Main.RecordID = Temp.RecordID
WHERE Main.ThirdPartyID IS NOT NULL

Answer 2

You could get a copy of the inserted data by OUTPUT-ing it to a table variable, then perform the update by joining to the original table. e.g:
DECLARE #inserted TABLE
(PKID INT
,RecordID INT
,ThirdPartyID INT
,Action VARCHAR(MAX)
,DateAdded DATE);
INSERT TestTable1
(RecordID
,ThirdPartyID
,Action
,DateAdded)
OUTPUT
inserted.PKID
,inserted.RecordID
,inserted.ThirdPartyID
,inserted.Action
,inserted.DateAdded
INTO #inserted
(PKID
,RecordID
,ThirdPartyID
,Action
,DateAdded)
VALUES
(1
,2
,NULL
,GETDATE());
UPDATE t
SET ThirdPartyID = 'Multiple Entries'
FROM #inserted i
JOIN TestTable1 t
ON i.RecordID = t.RecordID
WHERE t.ThirdPartyID IS NOT NULL;