Unfortunately, SQL Server does not have the SQL-92 syntax for a "SET
ROW()= ..." clause, so you do one column at a time.

UPDATE T1
  SET T1.v1 = (SELECT T2.v1
                 FROM T2
                WHERE T1.key = T2.key),
      T1.v2 = (SELECT T2.v2
                 FROM T2
                WHERE T1.key = T2.key)
WHERE T1.v3 LIKE '%'; -- strange predicate?

They have a version of the UPDATE.. FROM.. that appeared in Sybase and
other products.  Unfortunately, it is unpredictable, does not port and
does not match the semantivcs of other products with the same syntax.

MS SQL Server supports a proprietary syntax for its UPDATE statement which
uses a FROM clause similiar to that in a SELECT statement. Thus you could
do:

UPDATE t1
  SET v1 = t2.v1,
      v2 = t2.v2
 FROM t2
WHERE t2.key = t1.key
  AND t1.v3 LIKE '%' ;