// Advanced INDEX ON test — FOR condition + function expressions
FUNCTION Main()
   LOCAL i, nCount

   ? "=== Index Advanced Test ==="

   dbCreate("idxadv", {{"ID","N",6,0},{"FIRST","C",10,0},{"LAST","C",10,0},{"CITY","C",10,0}})
   USE "idxadv"
   FOR i := 1 TO 30
      APPEND BLANK
      FieldPut(1, i)
      FieldPut(2, {"John","Jane","Bob","Alice","Tom","Mary"}[Int(Mod(i-1,6))+1])
      FieldPut(3, {"Kim","Lee","Park","Choi","Yoon"}[Int(Mod(i-1,5))+1])
      FieldPut(4, {"Seoul","Tokyo","NYC"}[Int(Mod(i-1,3))+1])
   NEXT
   ? "Records:", RecCount()

   // 1. INDEX ON with UPPER()
   ? ""
   ? "--- 1. INDEX ON UPPER(LAST) ---"
   INDEX ON UPPER(LAST) TO idxadv_upper
   GO TOP
   ? "  First:", AllTrim(FieldGet(3))
   GO BOTTOM
   ? "  Last:", AllTrim(FieldGet(3))
   SEEK "KIM"
   ? "  SEEK KIM: Found=", Found()

   // 2. INDEX ON with concatenation
   ? ""
   ? "--- 2. INDEX ON LAST+FIRST ---"
   INDEX ON LAST+FIRST TO idxadv_combo
   GO TOP
   ? "  First:", AllTrim(FieldGet(3)), AllTrim(FieldGet(2))
   SEEK "Choi"
   ? "  SEEK Choi: Found=", Found(), "Name:", AllTrim(FieldGet(3)), AllTrim(FieldGet(2))

   // 3. INDEX ON with FOR condition
   ? ""
   ? "--- 3. INDEX ON LAST FOR CITY = Seoul ---"
   INDEX ON LAST TO idxadv_seoul FOR CITY = "Seoul"
   GO TOP
   nCount := 0
   DO WHILE !Eof()
      nCount++
      SKIP
   ENDDO
   ? "  Records in Seoul index:", nCount, "(expected 10 of 30)"
   GO TOP
   ? "  First Seoul:", AllTrim(FieldGet(3)), "City:", AllTrim(FieldGet(4))

   // 4. INDEX ON UPPER(LAST+FIRST) — nested function + concat
   ? ""
   ? "--- 4. INDEX ON UPPER(LAST+FIRST) ---"
   INDEX ON UPPER(LAST+FIRST) TO idxadv_full
   GO TOP
   ? "  First:", AllTrim(FieldGet(3)), AllTrim(FieldGet(2))
   SEEK "KIMJOHN"
   ? "  SEEK KIMJOHN: Found=", Found()

   USE
   ? ""
   ? "=== Done ==="
   RETURN NIL