使用asp.net mv在ado.net中选择带where子句的查询

问题描述

这是我的带条件子句的选择查询，每次我将其称为数据表为空且列表计数为0时，请更正我的选择查询或ado.net代码。我想从这些参数从sql Server获取数据，但我不知道我的SQL查询错误还是ado.net代码错误

public List<AdsModel> GetAds(string _location,Int64 _maxprice,Int64 _minprice,int _maxarea,int _minarea)
        {
            connection();
            List<AdsModel> AdsModelList = new List<AdsModel>();
            sqlCommand cmd = new sqlCommand("select * from propertydata_tbl where Location like '%@location%' and Price >= @minprice and Price <= @maxprice and Area >= @minarea and Area <= @maxarea",con);
            cmd.Parameters.AddWithValue("@location",_location);
            cmd.Parameters.AddWithValue("@minprice",_minprice);
            cmd.Parameters.AddWithValue("@maxprice",_maxprice);
            cmd.Parameters.AddWithValue("@minarea",_minarea);
            cmd.Parameters.AddWithValue("@maxarea",_maxarea);

            sqlDataAdapter da = new sqlDataAdapter(cmd);
            DataTable dt = new DataTable();
            con.open();
            da.Fill(dt);
            con.Close();

            if (dt != null)
            {
                foreach (DaTarow dr in dt.Rows)
                {

                    AdsModelList.Add(

                        new AdsModel
                        {
                            id = Convert.ToInt32(dr["Id"]),price = Convert.ToInt64(dr["Price"]),location = Convert.ToString(dr["Location"]),area = Convert.ToInt32(dr["Area"]),postdate = Convert.ToString(dr["Postdate"]),titlelink = Convert.ToString(dr["Titleline"]),adlink = Convert.ToString(dr["Adlink"])
                        }

                        );
                }

            }

            return AdsModelList;
        }

解决方法

ADO不会插入字符串，而是将单引号内的所有内容都视为发送给SQL的字符串文字。您应该从以下文字中提取@location：

SqlCommand cmd = new SqlCommand("select * from propertydata_tbl where Location like '%' + @location + '%' and Price >= @minprice and Price <= @maxprice and Area >= @minarea and Area <= @maxarea",con);
// Here --------------------------------------------------------------------------------^-----------^