C# MVC ADO.NET在插入值时预期参数错误

问题消息：消息“参数化查询”（@ProductName nvarchar（3）、@SupplierID nvarchar（4000）、@CategoryID）需要未提供的参数“@SupplierID”。字符串

我一直在尝试使用MVC操作将多个值插入到经典North wind表的产品表中。 列出该表时没有任何问题，但当我尝试使用scaffold-ed-Create-page（自动生成）插入值时，上面给出了错误

这是我的ProductController和AddProduct cshtml

控制器

public class ProductController : Controller
    {
        public string connectionString = @"Data Source = DESKTOP-O5J7OII\SQLEXPRESS01; Initial Catalog = NORTHWND; Integrated Security = True";
        //NORTHWNDEntities Kod = new NORTHWNDEntities();
        //Product x = new Product();

        public ActionResult Index(Product t = null)
        {


            DataTable tableProduct = new DataTable();
            using (SqlConnection sqlCon = new SqlConnection(connectionString))
            {
                sqlCon.Open();
                SqlDataAdapter sqlDA = new SqlDataAdapter("use NORTHWND SELECT * FROM Products Order By ProductID ASC", sqlCon);
                sqlDA.Fill(tableProduct);

            }

            return View(tableProduct);


            //var result = Kod.Products.Where(x => x.ProductID > 0).OrderBy(x => x.ProductID).ToList();


            //return View(result.ToList());
        }

        public ActionResult AddProduct()
        {
            return View(new WebApplication1.Product());
        }

        [HttpPost]
        public ActionResult AddProduct(Product productModel)
        {
            using (SqlConnection sqlCon = new SqlConnection(connectionString))
            {
                sqlCon.Open();
                string query = @"INSERT INTO Products VALUES(@ProductName,@SupplierID,@CategoryID,@QuantityPerUnit,@UnitPrice,@UnitsInStock,@UnitsOnOrder,@ReorderLevel)";
                SqlCommand sqlCmd = new SqlCommand(query, sqlCon);
                sqlCmd.Parameters.AddWithValue("@ProductName", productModel.ProductName);
                sqlCmd.Parameters.AddWithValue("@SupplierID", productModel.SupplierID);
                sqlCmd.Parameters.AddWithValue("@CategoryID", productModel.CategoryID);
                sqlCmd.Parameters.AddWithValue("@QuantityPerUnit", productModel.QuantityPerUnit);
                sqlCmd.Parameters.AddWithValue("@UnitPrice", productModel.UnitPrice);
                sqlCmd.Parameters.AddWithValue("@UnitsInStock", productModel.UnitsInStock);
                sqlCmd.Parameters.AddWithValue("@UnitsOnOrder", productModel.UnitsOnOrder);
                sqlCmd.Parameters.AddWithValue("@ReorderLevel", productModel.ReorderLevel);
                sqlCmd.Parameters.AddWithValue("@Discontinued", productModel.Discontinued);
                sqlCmd.ExecuteNonQuery();
            }
            return RedirectToAction("Index");
        }

和.cshtml

@model WebApplication1.Product

@using (Html.BeginForm()) 
{
    @Html.AntiForgeryToken()

    <div class="form-horizontal">
        <h4>Product</h4>
        <hr />
        @Html.ValidationSummary(true, "", new { @class = "text-danger" })
        <div class="form-group">
            @Html.LabelFor(model => model.ProductName, htmlAttributes: new { @class = "control-label col-md-2" })
            <div class="col-md-10">
                @Html.EditorFor(model => model.ProductName, new { htmlAttributes = new { @class = "form-control" } })
                @Html.ValidationMessageFor(model => model.ProductName, "", new { @class = "text-danger" })
            </div>
        </div>

        <div class="form-group">
            @Html.LabelFor(model => model.QuantityPerUnit, htmlAttributes: new { @class = "control-label col-md-2" })
            <div class="col-md-10">
                @Html.EditorFor(model => model.QuantityPerUnit, new { htmlAttributes = new { @class = "form-control" } })
                @Html.ValidationMessageFor(model => model.QuantityPerUnit, "", new { @class = "text-danger" })
            </div>
        </div>

        <div class="form-group">
            @Html.LabelFor(model => model.UnitPrice, htmlAttributes: new { @class = "control-label col-md-2" })
            <div class="col-md-10">
                @Html.EditorFor(model => model.UnitPrice, new { htmlAttributes = new { @class = "form-control" } })
                @Html.ValidationMessageFor(model => model.UnitPrice, "", new { @class = "text-danger" })
            </div>
        </div>

        <div class="form-group">
            @Html.LabelFor(model => model.Discontinued, htmlAttributes: new { @class = "control-label col-md-2" })
            <div class="col-md-10">
                <div class="checkbox">
                    @Html.EditorFor(model => model.Discontinued)
                    @Html.ValidationMessageFor(model => model.Discontinued, "", new { @class = "text-danger" })
                </div>
            </div>
        </div>

        <div class="form-group">
            <div class="col-md-offset-2 col-md-10">
                <input type="submit" value="Create" class="btn btn-default" />
            </div>
        </div>
    </div>
}

<div>
    @Html.ActionLink("Back to List", "Index")
</div>

@model WebApplication1.Product
@使用（Html.BeginForm（））
{
@Html.AntiForgeryToken（）
产品

@Html.ValidationSummary（true，“，new{@class=“text danger”}）
@LabelFor（model=>model.ProductName，htmlAttributes:new{@class=“control label col-md-2”}）
@EditorFor（model=>model.ProductName，new{htmlAttributes=new{@class=“form control”}}）
@Html.ValidationMessageFor（model=>model.ProductName，“，新{@class=“text danger”}）
@LabelFor（model=>model.QuantityPerUnit，htmlAttributes:new{@class=“controllabel col-md-2”}）
@EditorFor（model=>model.quantitypernit，new{htmlAttributes=new{@class=“form control”}}）
@Html.ValidationMessageFor（model=>model.QuantityPerUnit，“，new{@class=“text danger”}）
@LabelFor（model=>model.UnitPrice，htmlAttributes:new{@class=“controllabel col-md-2”}）
@EditorFor（model=>model.UnitPrice，new{htmlAttributes=new{@class=“form control”}}）
@Html.ValidationMessageFor（model=>model.UnitPrice，“，new{@class=“text danger”}）
@LabelFor（model=>model.contracted，htmlAttributes:new{@class=“controllabel col-md-2”}）
@EditorFor（model=>model.contracted）
@Html.ValidationMessageFor（model=>model.contracted，“，new{@class=“text danger”}）
}
@ActionLink（“返回列表”、“索引”）

---

感谢您的帮助并回复！：）

第一个问题是您提供的参数（9）超过了查询需要的参数（8）<代码>@不连续不是必需的

错误表示未提供

@SupplierID

。这意味着它有

null

值。检查db是否该列支持

null

值。然后将该行更改如下：

sqlCmd.Parameters.AddWithValue("@SupplierID", productModel.SupplierID ?? DBNull.Value);

?？？为空合并运算符。建议使用存储过程：

CREATE PROC AddProduct
@ProductName nvarchar(100),
@SupplierID int=null, /*This line inserts a DBNull, if parameter is null*/
@CategoryID int,
@QuantityPerUnit int,
@UnitPrice money,
@UnitsInStock int,
@UnitsOnOrder int,
@ReorderLevel int
BEGIN

INSERT INTO Products VALUES(@ProductName,@SupplierID,@CategoryID,@QuantityPerUnit,@UnitPrice,@UnitsInStock,@UnitsOnOrder,@ReorderLevel)

END

---

第一个问题是您提供的参数（9）比查询需要的参数（8）多<代码>@不连续不是必需的

错误表示未提供

@SupplierID

。这意味着它有

null

值。检查db是否该列支持

null

值。然后将该行更改如下：

sqlCmd.Parameters.AddWithValue("@SupplierID", productModel.SupplierID ?? DBNull.Value);

?？？为空合并运算符。建议使用存储过程：

CREATE PROC AddProduct
@ProductName nvarchar(100),
@SupplierID int=null, /*This line inserts a DBNull, if parameter is null*/
@CategoryID int,
@QuantityPerUnit int,
@UnitPrice money,
@UnitsInStock int,
@UnitsOnOrder int,
@ReorderLevel int
BEGIN

INSERT INTO Products VALUES(@ProductName,@SupplierID,@CategoryID,@QuantityPerUnit,@UnitPrice,@UnitsInStock,@UnitsOnOrder,@ReorderLevel)

END