一个简单的,适应多种数据库之间存取操作的数据库访问层[2]

  adataset := tmpquery;

  result := tmpquery.recordcount > 0;

end;
{ tdataaccess }

function tdataaccess.getsqlvalue(asqlstr: string;
  var avalue: variant): boolean;
var
  tmpdataset: tdataset;
  i: integer;
begin
  result := opensql(asqlstr, tmpdataset);
  try
    if result then
    begin
      avalue := vararraycreate([0, tmpdataset.fieldcount], varvariant);
      for i := 0 to tmpdataset.fieldcount - 1 do    // iterate
      begin
        avalue[i] := tmpdataset.fields[i].asstring;
      end;    // for
    end;
  finally
    tmpdataset.close;
    tmpdataset.free;
  end;

end;

function tdataaccess.getsqlvalue(asqlstr: string;
  var avalue: string): boolean;
var
  tmpdataset: tdataset;
begin
  result := opensql(asqlstr, tmpdataset);
  try
    if result then
      avalue := tmpdataset.fields[0].asstring;

  finally
    tmpdataset.close;
    tmpdataset.free;
  end;

end;