>Where to select them?
>You didn't select anything, you just store some data into variables :-)
>This while is the same as your just I didn't store the variables in EXISTS ()
>
>I am not sure what you try to do here. If you give me an example data and desired result maybe there is a solution w/o using cursors.

This is what I had to do:

DECLARE @lcField Char(40)
DECLARE @lcField2 Char(40)
DECLARE @lnNumero Integer
DECLARE @lnNumero2 Integer
DECLARE @loRecord nvarchar(128)

DECLARE loCursor CURSOR LOCAL FOR
SELECT Numero,Field,Field2 FROM Relation

OPEN loCursor
FETCH NEXT FROM loCursor INTO @lnNumero,@lcField,@lcField2
WHILE @@fetch_status = 0
BEGIN
   PRINT 'Update Relation '+convert(varchar,@lnNumero)+'.'

   SELECT @lnNumero2=Numero FROM Field WHERE Field=@lcField

   UPDATE Relation SET NoField=@lnNumero2 WHERE Numero=@lnNumero

   SELECT @lnNumero2=Numero FROM Field WHERE Field=@lcField2

   UPDATE Relation SET NoField2=@lnNumero2 WHERE Numero=@lnNumero

   FETCH NEXT FROM loCursor INTO @lnNumero,@lcField,@lcField2
END