c# - 将列表保存到数据库

Question

这是我目前所拥有的:

Veza.Open();
SqlCommand zadnjaN = new SqlCommand("SELECT TOP 1 id_n FROM Narudzba ORDER BY id_n DESC", Veza);
var id_zn = zadnjaN.ExecuteScalar(); //get 1 value for id_zn (last one entered)
List<int> proizvodi = new List<int>();
proizvodi = (List<int>)Session["kosarica"];
SqlCommand kupnja1 = new SqlCommand("INSERT INTO NarudzbaItemi ([narudzbaID], [proizvodID]) VALUES (@id_zn, @pro)", Veza);
for (int i = 0; i < proizvodi.Count; i++)
{
  kupnja1.Parameters.AddWithValue("pro", proizvodi[i]); //also tried @pro
  kupnja1.Parameters.AddWithValue("id_zn", id_zn); //@id_zn
  kupnja1.ExecuteNonQuery();
}
Veza.Close();

我收到一条消息，说变量名@pro 已全部声明。关键是，我需要将一个 int 项目列表插入到列 proizvodID 中，但是我多次在该列中插入一个值，我需要在列 narudzbaID 中多次插入一个不变的值，我从另一个表中获得最后增加的值。所有 3 列都是 int，Session 是 List int。使用 asp.net、c#、sql server 2008。

Answer 1

您不断在循环中添加参数。在第二次迭代中，@pro 已经定义。

试试这个:

Veza.Open();
object id_zn; //get 1 value for id_zn (last one entered)
using (SqlCommand zadnjaN = new SqlCommand("SELECT TOP 1 id_n FROM Narudzba ORDER BY id_n DESC", Veza))
{
    id_zn = zadnjaN.ExecuteScalar();
}
List<int> proizvodi = (List<int>)Session["kosarica"];
using (SqlCommand kupnja1 = new SqlCommand("INSERT INTO NarudzbaItemi ([narudzbaID], [proizvodID]) VALUES (@id_zn, @pro)", Veza))
{
    kupnja1.Parameters.Add("pro"); 
    kupnja1.Parameters.Add("id_zn");
    for (int i = 0; i < proizvodi.Count; i++)
    {
        kupnja1.Parameters["pro"].Value = proizvodi[i]; //also tried @pro
        kupnja1.Parameters["id_zn"].Value = id_zn; //@id_zn
        kupnja1.ExecuteNonQuery();
    }
}
Veza.Close();