The FOR statement executes a statement or group of statements
    once for each record in a record stream formed by a record
    selection expression. You can nest FOR statements within other
    FOR statements to establish relationships for outer joins.

    Your program can use either FOR statements or START_STREAM
    statements to establish record streams. You can use both methods
    in one program. However, you cannot use the FETCH statement
    to advance the pointer in a record stream established by a FOR
    statement. The FOR statement automatically advances to the next
    record.