>Fabio,
>
>now I get ERROR 1814 Queries of this type are not supported. It looks like he don't like ordr by or TOP.
>
>Agnes

CREATE CURSOR curSource (dDate D , nValue  I)
INSERT INTO curSource VALUES (DATE(2008,1,1),5)
INSERT INTO curSource VALUES (DATE(2008,1,10),3)

* THIS IS THE SQL CORRECT SOLUTION, BUT VFP SQL is too limited
SELECT;
 dDate;
, nValue - NVL((SELECT TOP 1 nValue FROM curSource WHERE dDate>X.dDate ORDER BY dDate),0);
 FROM curSource X;
 ORDER BY 1
 
* climbing on mirrors
 SELECT;
 X.dDate;
, X.nValue - NVL(X1.nValue,0);
 FROM curSource X;
 LEFT JOIN curSource X1 ON X1.dDate>X.dDate;
 WHERE X1.dDate=(SELECT MIN(dDate) FROM curSource WHERE dDate>X.dDate) OR X1.dDate IS NULL;
 ORDER BY 1