使用SqlDataReader和Label时“输入字符串的格式不正确”

Question

I'm joining two tables - Contact and RetailTrainingUserLevelMap in a Select statement.

(The common column in both is the RetailTrainingUserLevelID int)

SELECT Contact.IntranetUserName, Contact.CompanyName, RetailTrainingUserLevelMap.RetailTrainingUserLevel

FROM Contact

INNER JOIN RetailTrainingUserLevelMap ON Contact.RetailTrainingUserLevelID = RetailTrainingUserLevelMap.RetailTrainingUserLevelID

AND Contact.RetailTrainingUserLevelID = RetailTrainingUserLevelMap.RetailTrainingUserLevelID

WHERE (Contact.IntranetUserName = @IntranetUserName)

---

If I run this statement through Visual Studio Query Builder(the test query window), and enter a value for "IntranetUserName" I get:

IntranetUserName:
John Joe

CompanyName:
Acme Inc.

RetailTrainingUserLevel:
Manager

This is my desired output, so far so good.

If I use this same select statement in my .cs codebehind using a SqlDataReader to bind labels to Some of these columns like this:

SqlCommand comm;
        SqlConnection conn;
        string intranetConnectionString = ConfigurationManager.ConnectionStrings["DataConnect"].ConnectionString;
        conn = new SqlConnection(intranetConnectionString);
        comm = new SqlCommand("SELECT Contact.IntranetUserName, Contact.CompanyName, RetailTrainingUserLevelMap.RetailTrainingUserLevel FROM Contact INNER JOIN RetailTrainingUserLevelMap ON Contact.RetailTrainingUserLevelID = RetailTrainingUserLevelMap.RetailTrainingUserLevelID AND Contact.RetailTrainingUserLevelID = RetailTrainingUserLevelMap.RetailTrainingUserLevelID WHERE (Contact.IntranetUserName = @IntranetUserName)", conn);

        comm.Parameters.Add("@IntranetUserName", System.Data.SqlDbType.VarChar, 50);
        comm.Parameters["@IntranetUserName"].Value = memberLoginName;

        conn.Open();
        SqlDataReader reader = comm.ExecuteReader();
        while (reader.Read())
        {
            memberCompanyNameLabel.Text += reader["CompanyName"];
           userLevelLabel.Text += reader["RetailTrainingUserLevel"];
        }

        reader.Close();
        conn.Close();

I get the error "Input string was not in a correct format." here:
userLevelLabel.Text += reader["RetailTrainingUserLevel"];

What C# syntax needs to be changed here so I can get that value properly bound to my userLevelLabel?

Note: RetailTrainingUserLevelID int
RetailTrainingUserLevel varchar (50)

Thanks for your time and knowledge.

Answer 1

You sure reader["RetailTrainingUserLevel"] is not DBNull??

might want to do .ToString() on it before trying to add it to another string.

I would just do

userLevelLabel.Text += reader["RetailTrainingUserLevel"].ToString();