DELPHI提示列名无效，！

Question

      SelectSqlServer:='select * from userName where usernames="'+Txtusername+'"';//提示Txtusername值列名无效！真是想不通啊！
      form1.ADOQuery2.Close;
      form1.ADOQuery2.SQL.Clear;
      form1.ADOQuery2.SQL.Add(SelectSqlServer);
      form1.ADOQuery2.open;
      TxtName:=form1.ADOQuery2.Parameters.ParamByName('UserNames').Value;

Answer 1

看不明白,建议楼主把语句贴多些.可参考下面语句
       ADOquery1.SQL.Clear;
      ADOquery1.SQL.Add('select  *  from stuinfo  where 学号=:xh');
      ADOquery1.Parameters.ParamByName('xh').Value:=trim(edit1.Text);
      Adoquery1.Open;
      

Answer 2

SelectSqlServer:='select * from userName where usernames="'+Txtusername+'"';//提示Txtusername值
改写
SelectSqlServer:='select * from userName where usernames='+quotedstr(Txtusername)
或者
SelectSqlServer:='select * from userName where usernames='''+Txtusername+'''';(全部用单引号)

Answer 3

应该是字符串的拼接错误吧，连接符号用单引号。SelectSqlServer:='select * from userName where usernames='''+Txtusername+''' ';
or
SelectSqlServer:='select * from userName where usernames=:userstr';
{考虑一楼的办法}