Enable multi user management in c#

In the table users a MySql db for each user can be stored with a different color, for example:

Users       colors
Foo         green
Pluto       yellow
Foo         red

When the user is authenticated I need to know what color is associated with the user who logs on.

I used the List method to append the variable color for each user in this way:

List<string> colorList = new List<string>();

....

if (reader.HasRows)
{
    while (reader.Read())
    {
        Colors = reader["Colors"].ToString();
        colorList.Add(Colors.ToString());
    }

        ns = string.Join(", ", colorList.ToArray());
}

And everything works up here.

Now I need publish in a GridView all rows stored in Experience table where are stored the comments of all users for each color.

For example in the case of user Foo I need publish in GridView all comments stored in Experience table speaking of the colors red and green.

But I can't publish this GridView because if user is Foo I see only the comments on the red color and nothing comment for green color.

Thought with loop I have this output:

SELECT * FROM Experience WHERE Colors IN ('red');

SELECT * FROM Experience WHERE Colors IN ('green');

My code below.

Anybody know how can I resolve do this?

Can you suggest?

Can you help me?

Thank you in advance.

private DataSet RetrieveColors()
    {
        str = null;
        strArr = null;
        count = 0;

        str = ns == null ? "" : ns.ToString();
        char[] splitchar = { ',' };

        if (!string.IsNullOrEmpty(str))
        {
            strArr = str.Split(splitchar);
        }
        else
        {
            strArr = null;
        }

        for (count = 0; count <= strArr.Length - 1; count++)
        {
                sql = @" SELECT * FROM Experience WHERE Colors IN (?); ";
        }


        DataSet dsColors = new DataSet();

        using (OdbcConnection cn =
          new OdbcConnection(ConfigurationManager.ConnectionStrings["ConnMySQL"].ConnectionString))
        {
            cn.Open();

            using (OdbcCommand cmd = new OdbcCommand(sql, cn))
            {
                for (count = 0; count <= strArr.Length - 1; count++)
                {
                    cmd.Parameters.AddWithValue("param1", Server.UrlDecode(strArr[count].Trim()));
                }

                OdbcDataAdapter adapter = new OdbcDataAdapter(cmd);
                adapter.Fill(dsColors);
            }
        }

        return dsColors;
    }

Edit # 1

Users       colors
Foo         green
Pluto       yellow
Foo         red