如何判断字段是否存在？

[麦子VISA]

如何判断？

[aiirii]

Table1.Fields.FindField()

[raineyquanter]

function HaveFileld(Query:TDataSet;AFieldName:String):boolean;
var i:integer;
begin
Result:=False;
for i:=0 to Query.Fields.Count-1 do
begin
Result:=Result or (Query.Fields.Fields[i].DisplayName=AFieldName);
end;
end;

[coeltdit]

ADOTABLE1.Fields.CheckFieldName();

[麦子VISA]

function HaveFileld(Query:TDataSet;AFieldName:String):boolean;
-----------------------
我在单元中定义该函数，出错了，TDATASET类型未定义，是不是还需要引用什么东西的吧？

[Rail100]

uses ADO, DB;

[麦子VISA]

uses
Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
Dialogs, DB, ADODB, ImgList, ComCtrls, ToolWin, Grids, DBGrids, StdCtrls,
ExtCtrls;
-------------------------
我的引用

[麦子VISA]

unit Unit1;

interface

uses
Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
Dialogs,DB,ADODB, Grids, DBGrids, StdCtrls;

type
TForm1 = class(TForm)
ADOConnection1: TADOConnection;
ADODataSet1: TADODataSet;
DataSource1: TDataSource;
DBGrid1: TDBGrid;
Button1: TButton;
procedure Button1Click(Sender: TObject);
private
{ Private declarations }
Function ColumnExists(DataSet:TDateSet;sColumn:String):Boolean;

public
{ Public declarations }
end;

var
Form1: TForm1;

implementation

{$R *.dfm}
Function TForm1.ColumnExists(DataSet:TDateSet; sColumn:String):Boolean;
var
T:TField;
begin
T:=DataSet.FindField(sColumn);
if Assigned(T) then Result:=true else Result:=false;
end;

procedure TForm1.Button1Click(Sender: TObject);
begin
ADODataSet1.close;
ADODataSet1.CommandText:='select * from Dic_City';
ADODataSet1.Open;
if ColumnExists(ADODataSet1,'Code') then
showmessage('OK');
end;

end.
---------------------
ERROR：'Undeclared identifier:'TDataSet''

[whythinkwhy]

Function ColumnExists(DataSet:TDateSet;sColumn:String):Boolean; 好像应该改为
Function ColumnExists(adoDataSet:TADODateSet;sColumn:String):Boolean; 下面引用的也应该是ADODateSet 你前面定义的是TADODateSet

[officecn]

楼上几位说得都有道理，你还可以使用ADOX去读取表结构。
使用之前先用Import Type引入ADOX

[chinaandys]

create procedure isname
@name varchar(30)
as
begin
select [name] from syscolumns where id=object_id('tmp')
where [name]=@name
end