Question

Both source and destination tables have about 40 columns. No. of rows to be updated is about 20. Row count of Destination table is around 30k.

Is there a better (shorter query) approach to below?

UPDATE destination_table t1
SET 
field1 = (select field1 from src_table t2 where t2.pk = t1.pk),
field2 = (select field2 from src_table t2 where t2.pk = t1.pk),
... 
field40 = (select field40 from src_table t2 where t2.pk = t1.pk),
WHERE EXISTS (select 1 from src_table t2 where t2.pk = t1.pk)

Answer 1

You could use something like this:

UPDATE      dest
SET         dest.Field1 = src.Field1,
            dest.Field2 = src.Field2,
            dest.Field3 = src.Field3,
            dest.Field4 = src.Field4,
            dest.Field5 = src.Field5,
            dest.Field6 = src.Field6
FROM        destination_table dest
INNER JOIN  src_table src
ON          src.pk = dest.pk

You just need to add in the extra fields to update.