Using a subquery instead of a table name in an Oracle Update Statement

UPDATE
  TABLE1 a,
  TABLE2 b
SET
  a.COL1 = 'VALUE'
WHERE
  a.FK = b.PK
  AND b.COL2 IN ('SET OF VALUES')

UPDATE
  (
    SELECT
      a.COL1
    FROM
      TABLE1 a,
      TABLE2 b
    WHERE
      a.FK = b.PK
      AND b.COL2 IN ('SET OF VALUES')
  ) update_tbl
SET
  update_tbl.COL1 = 'VALUE'

UPDATE
  TABLE1 update_tbl
SET
  update_tbl.COL1 = 'VALUE'
WHERE
  EXISTS (
    SELECT
      1
    FROM
      TABLE1 a
      TABLE2 b
    WHERE
      a.FK = b.PK
      AND b.COL2 IN ('SET OF VALUES')
      AND update_tbl.PK = a.PK
  )

UPDATE TABLE1 a
SET a.COL1 = 'VALUE'
WHERE a.FK IN
( SELECT b.PK FROM TABLE2 b
  WHERE b.COL2 IN ('SET OF VALUES')
)

UPDATE
  (
    SELECT
      a.COL1, a.PKCOL
    FROM
      TABLE1 a,
      TABLE2 b
    WHERE
      a.FK = b.PK
      AND b.COL2 IN ('SET OF VALUES')
  ) update_tbl
SET
  update_tbl.COL1 = 'VALUE'

UPDATE
  TABLE1
SET
  COL1 = 'VALUE'
WHERE
  ROWID in
    (
    SELECT
      a.rowid
    FROM
      TABLE1 a,
      TABLE2 b
    WHERE
      a.FK = b.PK
      AND b.COL2 IN ('SET OF VALUES')
    )

UPDATE
  TABLE1 update_tbl
SET
  update_tbl.COL1 = 'VALUE'
WHERE
  (update_tbl.PK1, update_tbl.pk2) in(
                      select some_field1, some_field2
                      from some_table st
                      where st.some_fields = 'some conditions'
                      );

DECLARE

 /* Output variables to hold the result of the query: */
 a T1.e%TYPE;
 b T2.f%TYPE;
 c T2.g%TYPE;

 /* Cursor declaration: */
 CURSOR T1Cursor IS
   SELECT T1.e, T2.f, T2.g
   FROM T1, T2
   WHERE T1.id = T2.id AND T1.e <> T2.f

 FOR UPDATE;

BEGIN

  OPEN T1Cursor;

  LOOP

    /* Retrieve each row of the result of the above query
    into PL/SQL variables: */
    FETCH T1Cursor INTO a, b;

    /* If there are no more rows to fetch, exit the loop: */
    EXIT WHEN T1Cursor%NOTFOUND;

    /* Delete the current tuple: */
    DELETE FROM T1 WHERE CURRENT OF T1Cursor;

    /* Insert the reverse tuple: */
    INSERT INTO T1 VALUES(b, a);

    /* Here is my stuff using the variables to update my table */
    UPDATE T2
    SET T2.f = a
    WHERE T2.id = c;

  END LOOP;

  /* Free cursor used by the query. */
  CLOSE T1Cursor;

END;
.
run;