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Next

procedure Next;

Example​

procedure ProcessRows(const Data: TvxClientDataSet);
begin
  Data.First;
  while not Data.EOF do
  begin
    // Read the current row here.
    Data.Next;
  end;
end;

Usage​

Next attempts to move one record forward and updates EOF when no further record is available.

  • Use the canonical First; while not EOF do ...; Next pattern.
  • Ensure every loop path calls Next or exits to avoid an infinite loop.
  • Avoid calling repeatedly after EOF because the before-scroll callback still runs.

Usage guidance​

  • Use the canonical First; while not EOF do ...; Next pattern.
  • Ensure every loop path calls Next or exits to avoid an infinite loop.
  • Avoid calling repeatedly after EOF because the before-scroll callback still runs.
  • Do not read fields after Next has established EOF without checking the flag.
  • Processing code must decide how implicit posting of a pending edit should be handled.

Additional Technical Info​

Next is declared by hidden ancestor TDataSet and is normally used through a visible descendant such as TvxClientDataSet. It delegates to MoveBy(1) except during block-read mode.

Source-backed behaviour​

The normal path calls MoveBy(1), inheriting browse-mode auto-Post/Cancel, provider fetch, scroll events and boundary handling. When already EOF, MoveBy performs no forward work, but it still resolves browse mode and invokes DoBeforeScroll without the directional branch's matching DoAfterScroll. If no next record can be retrieved from a non-EOF position, EOF is set true.

A client dataset may fetch additional provider packets before determining EOF. TvxClientDataSet normally disables fetch-on-demand and loads the full result at open.

Prior moves backward. EOF is the forward boundary flag.

Official RTL references​

Created 2026-07-15