Another possible solution.

SELECT customer_id, 0 AS nRecordOrd  ;
	FROM Customer ;
	WHERE customer_id IN (16, 10, 12, 15, 8, 1) ;
	INTO CURSOR curCustormer READWRITE 


REPLACE nRecordOrd WITH 1 FOR customer_id = 16
REPLACE nRecordOrd WITH 2 FOR customer_id = 10
REPLACE nRecordOrd WITH 3 FOR customer_id = 12
REPLACE nRecordOrd WITH 4 FOR customer_id = 15
REPLACE nRecordOrd WITH 5 FOR customer_id = 8
REPLACE nRecordOrd WITH 6 FOR customer_id = 1

INDEX ON nRecordOrd TAG nRecordOrd

>

>select customer_id  ;
>  from Customer ;
> where customer_id in (16, 10, 12, 15, 8, 1) ;
>  into cursor curCustormer
>

>
>How can I order the result cursor according to data in the set of inlist expressions
>
>Thank in advance
>
>Ali Altun