Write values from database to Excel

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C#

SQL

ADO.NET

I am passing values from array list to my sql Query as Parameter. but it throws error as
"No mapping exists from object type System.String[] to a known managed provider native type."

Below is my code.

SqlConnection connection = new SqlConnection(ConfigurationManager.ConnectionStrings["MySQLConnectionString"].ConnectionString);
                string sqlconnection = "select EMP_CODE from Emp_Login where EMP_MGR_CODE='" + lblUsername.Text + "'";
                connection.Open();
                SqlCommand selectcmd = new SqlCommand(sqlconnection, connection);
                SqlDataReader myReader = selectcmd.ExecuteReader();
                //var result = selectcmd.ExecuteReader();
                List<string[]> employees = new List<string[]>();
                while (myReader.Read())
                {
                    string[] fields = new string[1];
                    fields[0] = myReader["EMP_CODE"].ToString();
                    employees.Add(fields);
                }
                // Now you have a list of arrays that you can iterate over
                foreach (string[] fields in employees)
                {
                    string id = fields[0];
                }

                myReader.Close();
                //result.Close();
                connection.Close();            
                query = "select a.UserId as EmpCode,b.EmployeeName,CONVERT(VARCHAR(10),a.LogDate,110) as AccessDate," +
                         " min(CONVERT(VARCHAR(10),a.LogDate,108)) as InTime,max(CONVERT(VARCHAR(10),a.LogDate,108)) as OutTime," +
                         " convert(varchar(8),(convert(datetime,max(a.LogDate),110) - convert(datetime,MIN(a.Logdate),110)),108) AS TotalHours" +
                         " from DeviceLogs as a,Employees as b where Cast(a.LogDate AS DATE) between '" + startdate + "' and '" + enddate + "' and a.UserId IN ({0}) and" +
                         " a.UserId=b.EmployeeCode group by b.EmployeeName,a.UserId,CONVERT(VARCHAR(10),a.LogDate,110)";
                string[] paramNames = employees.Select((s, i) => "@EMP_CODE" + i.ToString()).ToArray();
                cn.Open();
                string inClause = string.Join(",", paramNames);
                using (var command = new SqlCommand(string.Format(query, inClause), cn))
                {
                    for (int i = 0; i < paramNames.Length; i++)
                    {
                        command.Parameters.AddWithValue(paramNames[i], employees[i]);
                    }

                    SqlDataReader dr = command.ExecuteReader();
                    StringBuilder sb = new StringBuilder();
                    //Add Header          
                    for (int count = 0; count < dr.FieldCount; count++)
                    {
                        if (dr.GetName(count) != null)
                            sb.Append(dr.GetName(count));
                        if (count < dr.FieldCount - 1)
                        {
                            sb.Append(",");
                        }
                    }
                    Response.Write(sb.ToString() + "\n");
                    Response.Flush();
                    //Append Data
                    while (dr.Read())
                    {
                        sb = new StringBuilder();

                        for (int col = 0; col < dr.FieldCount - 1; col++)
                        {
                            if (!dr.IsDBNull(col))
                                sb.Append(dr.GetValue(col).ToString().Replace(",", " "));
                            sb.Append(",");
                        }
                        if (!dr.IsDBNull(dr.FieldCount - 1))
                            sb.Append(dr.GetValue(
                            dr.FieldCount - 1).ToString().Replace(",", " "));
                        Response.Write(sb.ToString() + "\n");
                        Response.Flush();
                    }
                    dr.Dispose();
                } 
            
            }