DELPHi 中 varchar转换为numeric

procedure TForm1.Button1Click(Sender: TObject);   var temp :double;         str:String;begin    with adoquery1 do       begin          close;          sql.Clear;          sql.Add('select * from table1 where ID='''+edit1.Text+'''');          open;          temp:=fieldByName('colA').AsFloat;           str:=floattostr(temp);          showmessage('取出来的值='+floattostr(temp));       end;    with  ADOCommand1  do       begin         adocommand1.CommandText:='insert table2 values (cast('''+str+''' as decimal(18,5)))';          //adocommand1.CommandText:='insert table2 values (''+temp+'')';            Execute;       end;end;

如果想像Java一样直接写到拼接到sql语句中不可取，现在实验得到的办法就是先转换为String类型，然后使用数据库的函数cast()来处理。
例子：select cast('20.37554' as decimal(18,5))