参数化会话和查询字符串

本文关键字：查询 字符串 会话 参数 | 更新日期: 2023-09-27 18:11:08

我正面临一个错误消息，我不知道原因与我的sql语句在行:

DACatPgeVIPLIST.Fill(dsCatPgeVIPLIST);

显示了这个信息，你能帮我一下吗?

参数化查询(@Country nvarchar(7),@Category nvarchar(4000))SELECT a.[AdsID],需要参数@Category，但没有提供。

代码:

if (Session["location"] != null)
{
    using (SqlConnection CatPgeVIPLISTsqlCON = new SqlConnection(cs))
    {
        CatPgeVIPLISTsqlCON.Open();
        SqlDataAdapter DACatPgeVIPLIST = new SqlDataAdapter("SELECT a.[AdsID], a.[Country], a.[State], a.[City], a.[AdsTit], SUBSTRING(a.[AdsDesc], 1, 70) as AdsDesc, a.[AdsPrice], a.[Img1] FROM [ads] as a INNER JOIN [UserInfo] as u on u.UID = a.UID WHERE a.[Country] = @Country and a.[Category] = @Category and u.VIP = 'Yes'", cs);
        string location = Convert.ToString(Session["location"]);
        string category = Request.QueryString["category"];
        DACatPgeVIPLIST.SelectCommand.Parameters.AddWithValue("@Country", location);
        DACatPgeVIPLIST.SelectCommand.Parameters.AddWithValue("@Category", category);
        DataSet dsCatPgeVIPLIST = new DataSet();
        DACatPgeVIPLIST.Fill(dsCatPgeVIPLIST);
        CatPgeVIPLIST.DataSource = dsCatPgeVIPLIST.Tables[0];
        CatPgeVIPLIST.DataBind();
    }
}

参数化会话和查询字符串

下面一行代码可以将null分配到category:

string category = Request.QueryString["category"];

您可以像这样绕过它，将null转换为空字符串:

string category = Convert.ToString(Request.QueryString["category"]);

或者您可以尝试传递DBNull.Value而不是null(未测试):

DACatPgeVIPLIST.SelectCommand.Parameters
               .AddWithValue("@Category", (object)category ?? DBNull.Value);
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