Question

我做了这样的功能

public int InsertData(CategoryPhoto catphoto)
{
    string ans = null;
    SqlCommand cmd = DataConnection.GetConnection().CreateCommand();
    cmd.CommandText = "prcCategoryPhoto";
    cmd.CommandType = CommandType.StoredProcedure;
    // cmd.Parameters.Add(new SqlParameter("@PhotoID", prdctphoto.PhotoID));
    cmd.Parameters.Add(new SqlParameter("@PhotoName", catphoto.PhotoName));
    //cmd.Parameters.Add(new SqlParameter("@LeftPhoto", prdctphoto.LeftPhoto));
    //cmd.Parameters.Add(new SqlParameter("@RightPhoto", prdctphoto.RightPhoto));
    //cmd.Parameters.Add(new SqlParameter("@BackPhoto", prdctphoto.BackPhoto));
    //cmd.Parameters.Add(new SqlParameter("@MaterialPhoto", prdctphoto.MaterialPhoto));
    cmd.Parameters.Add(new SqlParameter("@ExtName", catphoto.ExtName));
    cmd.Parameters.Add(new SqlParameter("@PhotoType", catphoto.PhotoType));
    cmd.Parameters.Add(new SqlParameter("@PhotoSize", catphoto.PhotoSize));
    cmd.Parameters.Add(new SqlParameter("@CategoryID", catphoto.CategoryID));
    ans = cmd.ExecuteScalar().ToString();
    //var result = cmd.ExecuteScalar(); 
    //ans = int.Parse(result.ToString());
    cmd.Dispose();
    DataConnection.CloseConnection();
    return ans;
}

在我的存储过程中是

create proc [dbo].[prcCategoryPhoto]
(
@PhotoName  Varchar(100),
@ExtName    Varchar(100),
@PhotoType  Varchar(100),
@PhotoSize  int,
@CategoryID varchar(20)
)
as
insert into CategoryPhoto(PhotoName,ExtName,PhotoType,PhotoSize,CategoryID) 
    values (@PhotoName,@ExtName,@PhotoType,@PhotoSize,@CategoryID)
select @@IDENTITY

写return ans时出错了不能隐式地将字符串转换为int

并撰写

return int.Parse(ans);

它给出了nvarchar无法转换为int的异常

Answer 1

现在尝试这个.... `

   public string InsertData(CategoryPhoto catphoto)
   {

    string ans = null;
    SqlCommand cmd = DataConnection.GetConnection().CreateCommand();
    cmd.CommandText = "prcCategoryPhoto";
    cmd.CommandType = CommandType.StoredProcedure;
    cmd.Parameters.Add(new SqlParameter("@PhotoName", catphoto.PhotoName));
    cmd.Parameters.Add(new SqlParameter("@ExtName", catphoto.ExtName));
    cmd.Parameters.Add(new SqlParameter("@PhotoType", catphoto.PhotoType));
    cmd.Parameters.Add(new SqlParameter("@PhotoSize", catphoto.PhotoSize));
    cmd.Parameters.Add(new SqlParameter("@CategoryID", catphoto.CategoryID));
    ans = cmd.ExecuteScalar().ToString();
    cmd.Dispose();
    DataConnection.CloseConnection();
    return ans;
  }`

Answer 2

尝试以下，首先改变你的程序，添加一个输出参数，如下所示，

create proc [dbo].[prcCategoryPhoto]
(
@PhotoName  Varchar(100),
@ExtName    Varchar(100),
@PhotoType  Varchar(100),
@PhotoSize  int,
@CategoryID varchar(20),
@ID INT OUTPUT
)
as
insert into CategoryPhoto(PhotoName,ExtName,PhotoType,PhotoSize,CategoryID) 
    values (@PhotoName,@ExtName,@PhotoType,@PhotoSize,@CategoryID)
select @ID = @@IDENTITY

接下来修改你的功能，

public int InsertData(CategoryPhoto catphoto)
{
    SqlCommand cmd = DataConnection.GetConnection().CreateCommand();
    cmd.CommandText = "prcCategoryPhoto";
    cmd.CommandType = CommandType.StoredProcedure;
    // cmd.Parameters.Add(new SqlParameter("@PhotoID", prdctphoto.PhotoID));
    cmd.Parameters.Add(new SqlParameter("@PhotoName", catphoto.PhotoName));
    //cmd.Parameters.Add(new SqlParameter("@LeftPhoto", prdctphoto.LeftPhoto));
    //cmd.Parameters.Add(new SqlParameter("@RightPhoto", prdctphoto.RightPhoto));
    //cmd.Parameters.Add(new SqlParameter("@BackPhoto", prdctphoto.BackPhoto));
    //cmd.Parameters.Add(new SqlParameter("@MaterialPhoto", prdctphoto.MaterialPhoto));
    cmd.Parameters.Add(new SqlParameter("@ExtName", catphoto.ExtName));
    cmd.Parameters.Add(new SqlParameter("@PhotoType", catphoto.PhotoType));
    cmd.Parameters.Add(new SqlParameter("@PhotoSize", catphoto.PhotoSize));
    cmd.Parameters.Add(new SqlParameter("@CategoryID", catphoto.CategoryID));

    cmd.Parameters.Add(new SqlParameter("@ID",System.Data.SqlDbType.Int));
    cmd.Parameters["@ID"].Direction=System.Data.ParameterDirection.Output;

    cmd.ExecuteNonQuery();
    var ans = cmd.Parameters["@ID"].Value;
    cmd.Dispose();
    DataConnection.CloseConnection();
    return Convert.ToInt32(ans);
}

Answer 3

在调试器中查看您的字符串（和）。好像你有一些无法转换为int的字符。你能将方法的返回类型从int更改为string吗？

Answer 4

您应该使用using关键字。它确保即使出现错误也会调用dispose方法（即引发异常）。

此外，@@Identity在任何情况下都会返回一个数值（根据MSDN），它应该可以转换为整数或bigint。所以我的建议是：

public Int64 InsertData(CategoryPhoto catphoto)
{
  using (var connection = DataConnection.GetConnection)
  {
    using (var cmd = connection.CreateCommand())
    {
      cmd.CommandText = "prcCategoryPhoto";
      cmd.CommandType = CommandType.StoredProcedure;
      cmd.Parameters.Add(new SqlParameter("@PhotoName", catphoto.PhotoName));
      cmd.Parameters.Add(new SqlParameter("@ExtName", catphoto.ExtName));
      cmd.Parameters.Add(new SqlParameter("@PhotoType", catphoto.PhotoType));
      cmd.Parameters.Add(new SqlParameter("@PhotoSize", catphoto.PhotoSize));
      cmd.Parameters.Add(new SqlParameter("@CategoryID", catphoto.CategoryID));
      return (Int64)cmd.ExecuteScalar();
    }
  }
}

如果您的identity-column是一个整数，您当然可以更改方法的签名以返回int。

Answer 5

替换

 public int InsertData(CategoryPhoto catphoto)

与

 public string InsertData(CategoryPhoto catphoto)

并遵循相同的依赖...

Answer 6

ScoapIdentity将返回您的primarykey值，因此数据类型为int，因此您需要声明为int变量（不是字符串变量）。

所以将此行string ans = null;替换为int ans = null;

并且还需要更改此行

ans = Convert.ToInt32(cmd.ExecuteScalar());

如何在方法中返回字符串值？

6 个答案: