Listing A: Example of Conditional Action

MERGE dbo.Customers AS TGT
USING dbo.CustomersStage AS SRC
  ON TGT.custid = SRC.custid
WHEN MATCHED AND 
       (   TGT.companyname <> SRC.companyname
        OR TGT.phone       <> SRC.phone
        OR TGT.address     <> SRC.address) THEN
  UPDATE SET
    TGT.companyname = SRC.companyname,
    TGT.phone = SRC.phone,
    TGT.address = SRC.address
WHEN NOT MATCHED THEN 
  INSERT (custid, companyname, phone, address)
  VALUES (SRC.custid, SRC.companyname, SRC.phone, SRC.address);