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C# 方法错误,使用mysql_C#_Mysql - Fatal编程技术网

C# 方法错误,使用mysql

C# 方法错误,使用mysql,c#,mysql,C#,Mysql,我对函数进行了如下编码,我得到了一个错误,我试图通过这个返回字符串的方法从数据库中获取项目的详细信息 public static string GetItemDetails(int i_id, string i_name) { MySqlConnection SQL_con = new MySqlConnection(VPconfig.sql_conns); string[] ItemData = null; i_name = i_

我对函数进行了如下编码,我得到了一个错误,我试图通过这个返回字符串的方法从数据库中获取项目的详细信息

    public static string GetItemDetails(int i_id, string i_name)
    {
        MySqlConnection SQL_con = new MySqlConnection(VPconfig.sql_conns);
        string[] ItemData = null;
        i_name = i_name == null ? string.Empty : i_name;
        i_id = i_id == 0 ? 0 : i_id;

        try
        {
            if(i_id != 0)
            {
                //get Item details by ID
                string query = "SELECT * FROM items WHERE id="+i_id;
                MySqlCommand xv = new MySqlCommand(query, SQL_con);
                SQL_con.Open();
                MySqlDataReader rdr = xv.ExecuteReader();
                while(rdr.Read())
                {
                    ItemData[0] = rdr.GetString("id");
                    ItemData[1] = rdr.GetString("iname");
                    ItemData[2] = rdr.GetString("iprice");
                }
                SQL_con.Close();

                string master = ItemData[0] +"*"+ ItemData[1] +"*"+ ItemData[2];

                return master;//Return format ID*NAME*PRICE
            }
            else if(i_name != string.Empty)
            {
                //get Item details by Name
                string query = "SELECT * FROM items WHERE iname=" + i_name;
                MySqlCommand xv = new MySqlCommand(query, SQL_con);
                SQL_con.Open();
                MySqlDataReader rdr = xv.ExecuteReader();
                while (rdr.Read())
                {
                    ItemData[0] = rdr.GetString("id");
                    ItemData[1] = rdr.GetString("iname");
                    ItemData[2] = rdr.GetString("iprice");
                }
                SQL_con.Close();

                string master = ItemData[0] + "*" + ItemData[1] + "*" + ItemData[2];

                return master;//Return format ID*NAME*PRICE
            }
            else
            {
                MessageBox.Show("No Items! found with ID/Name: " + i_id + i_name);
            }

            //if nothing
            return null;
        }
        catch(Exception ex)
        {
            MessageBox.Show("Error Code: 17 "+ex.Message);

            //if nothing
            return null;
        }
现在,如果我传递以下参数,则显示错误“错误代码:17对象引用未设置为对象的实例” 基本上是从渔获物

string xv = VPfunctions.GetItemDetails(5, string.Empty);
ta.Text = xv;

谢谢。

引发异常,因为您用null声明了字符串数组,然后在DataReader循环中赋值

因此,这一行:

string[] ItemData = null;
应更改为以下内容:

string[] ItemData = new string[5];

你知道如何使用调试器吗?你能检查object ref的内部异常吗?无论我传递什么数据,错误都是一样的。非常感谢,问题已经解决了。