five/_FiveSql2/test/test_null_order.prg

// Regression test for NULL ordering in ORDER BY.
// Both the Go fast path (SqlOrderBy) and the PRG fallback
// (SqlRowCompare) must produce the same order and honor explicit
// NULLS FIRST/LAST from SQL:2003.
//
// Default (no NULLS spec): NULLs sort as the largest value — last in
// ASC, first in DESC. Matches PostgreSQL default and the legacy PRG
// SqlRowCompare behavior that predates the Go port.

STATIC s_nPass  := 0
STATIC s_nFail  := 0
STATIC s_nTotal := 0

PROCEDURE Main()

   ErrorBlock( {|e| QOut( "TRAP: " + e:description + " " + e:operation ), Break(e) } )

   ? "================================================================"
   ? "  FiveSql NULL Ordering Test"
   ? "================================================================"
   ?

   SetupData()

   // Diagnostic: show what score column actually contains after UPDATE,
   // then what ORDER BY score ASC produces.
   LOCAL aR := five_SQL( "SELECT name, score FROM nullord" )
   LOCAL i, aRows
   ? "Raw rows:"
   IF ValType( aR ) == "A" .AND. Len( aR ) >= 2
      aRows := aR[ 2 ]
      FOR i := 1 TO Len( aRows )
         ? "  name=" + AllTrim( aRows[ i ][ 1 ] ), "score=" + ;
           iif( aRows[ i ][ 2 ] == NIL, "NIL", LTrim( Str( aRows[ i ][ 2 ] ) ) )
      NEXT
   ENDIF
   ?
   aR := five_SQL( "SELECT name, score FROM nullord ORDER BY score" )
   ? "ORDER BY score ASC:"
   IF ValType( aR ) == "A" .AND. Len( aR ) >= 2
      aRows := aR[ 2 ]
      FOR i := 1 TO Len( aRows )
         ? "  name=" + AllTrim( aRows[ i ][ 1 ] ), "score=" + ;
           iif( aRows[ i ][ 2 ] == NIL, "NIL", LTrim( Str( aRows[ i ][ 2 ] ) ) )
      NEXT
   ENDIF
   ?

   TestDefaultAsc()
   TestDefaultDesc()
   TestNullsFirstAsc()
   TestNullsLastDesc()

   ?
   ? "================================================================"
   ? "  Results:", LTrim(Str(s_nPass)), "/", LTrim(Str(s_nTotal)), "passed"
   ? "================================================================"

   CleanupData()
RETURN


STATIC PROCEDURE SetupData()
   LOCAL aFields

   aFields := { ;
      {"NAME",   "C", 20, 0}, ;
      {"SCORE",  "N",  6, 0} }
   dbCreate( "nullord", aFields )
   USE "nullord" NEW EXCLUSIVE
   APPEND BLANK ; REPLACE NAME WITH "A", SCORE WITH 10
   APPEND BLANK ; REPLACE NAME WITH "B", SCORE WITH 30
   APPEND BLANK ; REPLACE NAME WITH "C"
   APPEND BLANK ; REPLACE NAME WITH "D", SCORE WITH 20
   APPEND BLANK ; REPLACE NAME WITH "E"
   CLOSE ALL

   // Null out C and E via UPDATE — SCORE column goes from numeric 0 to NIL.
   five_SQL( "UPDATE nullord SET score = NULL WHERE name = 'C'" )
   five_SQL( "UPDATE nullord SET score = NULL WHERE name = 'E'" )
RETURN


STATIC PROCEDURE CleanupData()
   CLOSE ALL
   FErase( "nullord.dbf" )
RETURN


STATIC FUNCTION NameOrder( aResult )
   LOCAL cOut := "", i, aRows
   IF ValType( aResult ) == "A" .AND. Len( aResult ) >= 2
      aRows := aResult[ 2 ]
      FOR i := 1 TO Len( aRows )
         cOut += AllTrim( aRows[ i ][ 1 ] )
      NEXT
   ENDIF
RETURN cOut


STATIC PROCEDURE Check( cLabel, cGot, cWant )
   s_nTotal++
   IF cGot == cWant
      s_nPass++
      ? "  PASS:", cLabel, "→", cGot
   ELSE
      s_nFail++
      ? "  FAIL:", cLabel, "→ got", cGot, "want", cWant
   ENDIF
RETURN


// Induce NULL via NULLIF(score, 0) — DBF N fields can't store NULL, so
// we turn the sentinel 0 into NULL at projection time. C and E have
// score=0 → projected s = NULL.

STATIC PROCEDURE TestDefaultAsc()
   LOCAL aR := five_SQL( "SELECT name, NULLIF(score, 0) AS s FROM nullord ORDER BY s" )
   // Default ASC: NULLs sort as largest → non-NULLs first (A=10, D=20, B=30), then NULLs (C, E)
   Check( "default ASC (NULLs last)", NameOrder( aR ), "ADBCE" )
RETURN


STATIC PROCEDURE TestDefaultDesc()
   LOCAL aR := five_SQL( "SELECT name, NULLIF(score, 0) AS s FROM nullord ORDER BY s DESC" )
   // Default DESC: NULLs sort as largest → NULLs first (C, E), then descending (B=30, D=20, A=10)
   Check( "default DESC (NULLs first)", NameOrder( aR ), "CEBDA" )
RETURN


STATIC PROCEDURE TestNullsFirstAsc()
   LOCAL aR := five_SQL( "SELECT name, NULLIF(score, 0) AS s FROM nullord ORDER BY s ASC NULLS FIRST" )
   Check( "ASC NULLS FIRST", NameOrder( aR ), "CEADB" )
RETURN


STATIC PROCEDURE TestNullsLastDesc()
   LOCAL aR := five_SQL( "SELECT name, NULLIF(score, 0) AS s FROM nullord ORDER BY s DESC NULLS LAST" )
   Check( "DESC NULLS LAST", NameOrder( aR ), "BDACE" )
RETURN