使用select（PHP和MySQL）输入查询插入中的所有数据值

I'm using PHP and Mysql to export my data in 2 tables. But I have a problem, only 1 line of data is exported. Even though in "select" table I have 5 lines of data.

mysqli_query($koneksi,"insert into booking_v2
                (booking_v2.DC,booking_v2.PO,booking_v2.VEND_NAME,booking_v2.KEY) 
                select distinct on_order.DC, on_order.PO, on_order.VEND_NAME, 
                    concat(on_order.PO,on_order.DC) 
                from on_order 
                 where on_order.VEND_NAME = '$VEND_NAME' 
                and on_order.SCHED_DATE = '$sched_date' 
                group by on_order.VEND_NAME") 

        or die ("DUPLICATE DATA");

How do I export all the lines?