代码如下
procedure TForm1.Button1Click(Sender: TObject);
var
le:string;
begin
adoquery1.SQL.Clear;
adoquery1.SQL.Add('select * from dj_km');
adoquery1.Active:=true;
adoquery1.Open;
adoquery1.First;
le:=adoquery1.fieldbyname('kmmm').AsString;
edit1.text:=le;
end;
上面这段代码可以执行,可是如果在edit1.text:=le前加上
adoquery1.SQL.Clear;
adoquery1.SQL.Add('select * from dj_km where kmmm=substring(le,1,3)');
adoquery1.Active:=true;
adoquery1.Open;
le:=adoquery1.fieldbyname('kmmc').AsString;
却会出错。加上去后的整段代码如下,
procedure TForm1.Button1Click(Sender: TObject);
var
le:string;
begin
adoquery1.SQL.Clear;
adoquery1.SQL.Add('select * from dj_km');
adoquery1.Active:=true;
adoquery1.Open;
adoquery1.First;
le:=adoquery1.fieldbyname('kmmm').AsString;
adoquery1.SQL.Clear;
adoquery1.SQL.Add('select * from dj_km where kmmm=substring(le,1,3)');
adoquery1.Active:=true;
adoquery1.Open;
le:=adoquery1.fieldbyname('kmmc').AsString;
edit1.text:=le
end;
注:dj_km是sql server 2000里的表,kmmm,kmmc是其中的两个varchar字段,涉及到的组件已建立。
procedure TForm1.Button1Click(Sender: TObject);
var
le:string;
begin
adoquery1.SQL.Clear;
adoquery1.SQL.Add('select * from dj_km');
adoquery1.Active:=true;
adoquery1.Open;
adoquery1.First;
le:=adoquery1.fieldbyname('kmmm').AsString;
edit1.text:=le;
end;
上面这段代码可以执行,可是如果在edit1.text:=le前加上
adoquery1.SQL.Clear;
adoquery1.SQL.Add('select * from dj_km where kmmm=substring(le,1,3)');
adoquery1.Active:=true;
adoquery1.Open;
le:=adoquery1.fieldbyname('kmmc').AsString;
却会出错。加上去后的整段代码如下,
procedure TForm1.Button1Click(Sender: TObject);
var
le:string;
begin
adoquery1.SQL.Clear;
adoquery1.SQL.Add('select * from dj_km');
adoquery1.Active:=true;
adoquery1.Open;
adoquery1.First;
le:=adoquery1.fieldbyname('kmmm').AsString;
adoquery1.SQL.Clear;
adoquery1.SQL.Add('select * from dj_km where kmmm=substring(le,1,3)');
adoquery1.Active:=true;
adoquery1.Open;
le:=adoquery1.fieldbyname('kmmc').AsString;
edit1.text:=le
end;
注:dj_km是sql server 2000里的表,kmmm,kmmc是其中的两个varchar字段,涉及到的组件已建立。
le:=adoquery1.fieldbyname('kmmm').AsString;
adoquery1.Close; //加上这一句试试
adoquery1.SQL.Clear;
var
le:string;
begin
adoquery1.SQL.Clear;
adoquery1.SQL.Add('select * from dj_km');
adoquery1.Active:=true;
adoquery1.Open;
adoquery1.First;
le:=adoquery1.fieldbyname('kmmm').AsString;
//添加代码如下:
AdoQuery1.Close;
// adoquery1.SQL.Clear;
adoquery1.SQL.Add('select * from dj_km where kmmm=substring(le,1,3)');
adoquery1.Active:=true;
adoquery1.Open;
le:=adoquery1.fieldbyname('kmmc').AsString;
edit1.text:=le
end;
adoquery1.SQL.Add('select * from dj_km where kmmm=substring('''+le+''',1,3)');
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