DO CASE
   CASE MAX(preco1, preco2, preco3) >= preco4 .and. preco4 # 0
      ** test price 4, this is the biggest
      MESSAGEBOX( "O price 4 must be bigger than 1, 2 e 3.)
      REPLACE min4 WITH 0, ;
              hs4 WITH 0, ;
              preco4 WITH 0
   CASE MAX(preco1, preco2) >= preco3 .and. preco3 # 0
      ** test price 3
      MESSAGEBOX( "price 3 must be bigger than prices ")
      REPLACE min3 WITH 0, ;
              hs3 WITH 0, ;
              preco3 WITH 0
   CASE preco1 >= preco2 .and. preco2 # 0
      ** test price 1 , this is the lowest
      MESSAGEBOX( "price 2 must be bigger than price 1 ")
      REPLACE min2 WITH 0, ;
              hs2 WITH 0, ;
              preco2 WITH 0
ENDCASE
ThisForm.Refresh()