我的删除查询不起作用

Question

I,m designing a CMS(campus Management System) and i wana delete some record...but its neither working nor generate any error...just return zero in "result " varaiable mentioned in code

public void DeleteAnnouncement(BusinessObject bo)
    {
        string ConnStr = Connection();
        SqlConnection conn = new SqlConnection(ConnStr);
        conn.Open();
        string query = "Delete from Anouncement where AnnouncementID=@i";


        SqlCommand cmd = new SqlCommand(query, conn);

        SqlParameter p1 = new SqlParameter("i", bo.A_ID);


        cmd.Parameters.Add(p1);

        int result = cmd.ExecuteNonQuery();
        conn.Close();

        if (result > 0)
        {
            Console.WriteLine("\n\n\t============================================");
            Console.WriteLine("\tAnnouncement Deleted");
            Console.WriteLine("\t============================================\n\n");
        }
    }

Answer 1

SqlParameter p1 = new SqlParameter("i", bo.A_ID);

您在参数名称前缺少“@”。

Correct: SqlParameter p1 = new SqlParameter("@i", bo.A_ID);

Answer 2

Your code works and deletes a record from Anouncement table, if AnnouncementID matches with the value of bo.A_ID , if value of bo.A_ID doesn't match with AnnouncementID , cmd.ExecuteNonQuery(); returns 0 . If it's not deleting that means AnnouncementID doesn't match with the value of bo.A_ID .

But I suggest improve you code through using statement, this using statement ensures that Dispose is called even if an exception occurs while methods on the object are called.

string ConnStr = Connection();
string query = "Delete from Anouncement where AnnouncementID=@i";
using (SqlConnection conn = new SqlConnection(ConnStr))
{
     using (SqlCommand cmd = new SqlCommand(query, conn))
     {
         try
            {
                SqlParameter p1 = new SqlParameter("i", bo.A_ID);
                cmd.Parameters.Add(p1);
                conn.Open();
                int result = cmd.ExecuteNonQuery();
                conn.Close();

                if (result > 0)
                {
                    Console.WriteLine 
                    ("\n\n\t============================================");
                    Console.WriteLine("\tAnnouncement Deleted");
                    Console.WriteLine 
                    ("\t============================================\n\n");
                    }
            }
            catch (Exception ex)
            {
               //Do your exception handling work
            }
      }
}