The result of a singleton select returned more than 1 value

  Explanation:  A singleton select statement (SELECT...INTO) may
  only return 1 row of values.  The result table for this
  singleton select contains more than one row.

  User Action:  Either embed the SELECT statement (without the
  INTO clause) in a DECLARE CURSOR statement and process it with
  OPEN and FETCH statements, or modify the SELECT statement so it
  will return only one row.