Store Procedure to DataTable Helper

DataUtil.cs

using System;
using System.Data;
using System.Data.SqlClient;
using System.Linq;
using System.Reflection;

public static class DataUtil
{
    public static T Fill<T>(string procedureName, string connectionString, object values = null, object mappings = null) where T : DataSet, new()
    {
        T ds = new T();

        // initialize connection
        using (var conn = new SqlConnection(connectionString)
        {
            using (var comm = new SqlCommand(procedureName, conn))
            {
                comm.CommandType = CommandType.StoredProcedure;
                comm.AddParameters(values);

                var da = new SqlDataAdapter(comm);
                conn.Open();

                if (mappings == null)
                {
                    da.TableMappings.Add("Table", ds.Tables[0].TableName);
                }
                else
                {
                    foreach (var pi in mappings.GetType().GetMembers().OfType<PropertyInfo>())
                    {
                        var parameter = pi.Name;
                        var value = pi.GetValue(mappings, null).ToString();
                        da.TableMappings.Add(parameter, value);
                    }
                }

                // fill data set and dispose
                da.Fill(ds);
                conn.Close();
            }
        }

        return ds;
    }

    public static SqlCommand AddParameters(this SqlCommand comm, object values)
    {
        comm.Parameters.Clear();

        if (values != null)
        {
            foreach (var pi in values.GetType().GetMembers().OfType<PropertyInfo>())
            {
                var parameter = pi.Name;
                var value = pi.GetValue(values, null);

                SqlDbType type;
                if (value is int)
                {
                    type = SqlDbType.Int;
                }
                else if (value is bool)
                {
                    type = SqlDbType.Bit;
                }
                else if (value is DateTime)
                {
                    type = SqlDbType.DateTime;
                }
                else if (value is float)
                {
                    type = SqlDbType.Float;
                }
                else if (value is byte)
                {
                    type = SqlDbType.TinyInt;
                }
                else if (value is string)
                {
                    type = SqlDbType.VarChar;
                    if (value == null)
                    {
                        value = System.Data.SqlTypes.SqlString.Null;
                    }
                }
                else if (value is int?)
                {
                    type = SqlDbType.Int;
                    if (value == null)
                    {
                        value = System.Data.SqlTypes.SqlInt32.Null;
                    }
                }
                else if (value is DateTime?)
                {
                    type = SqlDbType.DateTime;
                    if (value == null)
                    {
                        value = System.Data.SqlTypes.SqlDateTime.Null;
                    }
                }
                else if (value is float?)
                {
                    type = SqlDbType.Float;
                    if (value == null)
                    {
                        value = System.Data.SqlTypes.SqlDecimal.Null;
                    }
                }
                else if (value is byte?)
                {
                    type = SqlDbType.TinyInt;
                    if (value == null)
                    {
                        value = System.Data.SqlTypes.SqlInt16.Null;
                    }
                }
                else
                {
                    throw new InvalidOperationException("type from parameter " + parameter + " not supported.");
                }

                // add parameter
                comm.Parameters.Add("@" + parameter, type).Value = value;
            }
        }

        return comm;
    }
}