DateTime? dt2 = DateTime.Now;

dt2.GetValueOrDefault().ToString("yyyy-MM-dd");

public ViewResult index()

{

    var db = new db_context();

    var model = db.test;

    return View(model);

}

<table border="1" cellpadding="6" cellspacing="0" bordercolor="#CCC" style="border-collapse:collapse;">

    <tr>

        <th>

            @Html.DisplayNameFor(model => model.test_title)

        </th>

        <th>

            @Html.DisplayNameFor(model => model.create_time)

        </th>

        <th>

            @Html.DisplayNameFor(model => model.update_time)

        </th>

        <th></th>

    </tr>

    @foreach (var item in Model)

    {

        <tr>

            <td>

                @Html.DisplayFor(modelItem => item.test_title)

            </td>

            <td>

                @Html.DisplayFor(modelItem => item.create_time)

            </td>

            <td>

                @item.update_time.GetValueOrDefault().ToString("yyyy-MM-dd HH:mm")

            </td>

            <td>

                @Html.ActionLink("Edit", "Edit", new { id = item.id }) |

                @Html.ActionLink("Details", "Details", new { id = item.id }) |

                @Html.ActionLink("Delete", "Delete", new { id = item.id })

            </td>

        </tr>

    }

</table>