It's good pratics to use exists before an update?

Hi @first100
As Tom said,there no need to check if a record exists before update.
If you have lots of records and don't want to manually check one record at a time to see if data in a certain column already exist.
You could use a left join (or EXISTS etc...) from the source to the destination table on the id column to check if you have a matching row or not.
You can also have a look at the MERGE statement: https://msdn.microsoft.com/en-us/library/bb510625.aspx
Also,here is a link which is related to this thread : If Exists before Update or Delete?

Best regards,
LiHong

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Hi @first100 ,

Here is one way to handle it.
It will update rows just and only if there are some differences in place.

SQL

-- DDL and sample data population, start  
DECLARE @Source TABLE (APK INT IDENTITY PRIMARY KEY, ID_NUMBER INT, UpdatedOn DATETIMEOFFSET(3));  
DECLARE @Target TABLE (APK INT IDENTITY PRIMARY KEY, ID_NUMBER INT, UpdatedOn DATETIMEOFFSET(3));  
  
INSERT INTO @Source (ID_NUMBER)  
VALUES (null), (null), (7), (7), (5);  
  
INSERT INTO @Target (ID_NUMBER)  
VALUES (null), (7), (null), (7), (4);  
-- DDL and sample data population, end  
  
SELECT * FROM @Source;  
SELECT * FROM @Target;  
  
UPDATE T   
SET T.ID_NUMBER = S.ID_NUMBER  
   , T.UpdatedOn = SYSDATETIMEOFFSET()  
FROM @Target AS T  
    INNER JOIN @Source AS S  
      ON T.APK = S.APK  
WHERE NOT EXISTS (SELECT S.* INTERSECT SELECT T.*);  
  
-- test  
SELECT * FROM @Target;