there is another relation named <str> in this database

  Explanation:  The relation name  you  tried  to  define  already
  exists.   If the named table is a temporary table then it may be
  that a previous drop statement for a temporary table of the same
  name needs to be committed or rolled back.

  User Action:  Use another relation name.  Or in the  case  of  a
  temporary  table  the  user  may  need  to  commit or rollback a
  previous drop statement.