C# 错误：在命令执行期间遇到致命错误

错误：在命令执行期间遇到致命错误 这是我的密码：

 public static int AddCustomer(Customer customer)
    {
        MySqlConnection connection = MySqlCommand.GetConnection();
        string insertStatement =
            "INSERT INTO customer (CUSTOMER_FIRST_NAME, CUSTOMER_LAST_NAME, CUSTOMER_CITY, CUSTOMER_STATE, CUSTOMER_STREET_NUMBER, CUSTOMER_STREET, CUSTOMER_PHONE) " +
            "VALUES (@CUSTOMER_FIRST_NAME, @CUSTOMER_LAST_NAME, @CUSTOMER_CITY, @CUSTOMER_STATE, @CUSTOMER_STREET_NUMBER, @CUSTOMER_STREET, @CUSTOMER_PHONE)";
        MySql.Data.MySqlClient.MySqlCommand insertCommand =
            new MySql.Data.MySqlClient.MySqlCommand(insertStatement, connection);
        insertCommand.Parameters.AddWithValue(
            "@CUSTOMER_FIRST_NAME", customer.FirstName);
        insertCommand.Parameters.AddWithValue(
           "@CUSTOMER_LAST_NAME", customer.LastName);
        insertCommand.Parameters.AddWithValue(
            "@CUSTOMER_STREET_NUMBER", customer.StreetNumber);
        insertCommand.Parameters.AddWithValue(
             "@CUSTOMER_STREET_NAME", customer.Street);
        insertCommand.Parameters.AddWithValue(
            "@CUSTOMER_CITY", customer.City);
        insertCommand.Parameters.AddWithValue(
            "@CUSTOMER_STATE", customer.State);
        insertCommand.Parameters.AddWithValue(
            "@CUSTOMER_PHONE", customer.Phone);

        try
        {
            connection.Open();
            insertCommand.ExecuteNonQuery();
            string selectStatement =
               "SELECT MAX(CUST_ID) FROM customer";
            MySql.Data.MySqlClient.MySqlCommand selectCommand =
                new MySql.Data.MySqlClient.MySqlCommand(selectStatement, connection);
            int customerID = Convert.ToInt32(selectCommand.ExecuteScalar());
            return customerID;
        }
        catch (MySqlException ex)
        {
            throw ex;
        }
        finally
        {
            connection.Close();
        }
    }
    /// <summary>
    /// 
    /// </summary>
    /// <param name="oldCustomer"></param>
    /// <param name="newCustomer"></param>
    /// <returns></returns>
    public static bool UpdateCustomer(Customer oldCustomer, 
        Customer newCustomer)
    {
        MySqlConnection connection = MySqlCommand.GetConnection();
        string updateStatement =
            "UPDATE customer SET " +
            "CUSTOMER_FIRST_NAME = @NewCUSTOMER_FIRST_NAME, " +
            "CUSTOMER_LAST_NAME = @NewCUSTOMER_LAST_NAME, " +
            "CUSTOMER_STREET = @NewCUSTOMER_STREET, " +
            "CUSTOMER_STREET_NUMBER = @vCUSTOMER_STREET_NUMBER" +
            "CUSTOMER_CITY = @NewCUSTOMER_CITY, " +
            "CUSTOMER_STATE = @NewCUSTOMER_STATE, " +
            "CUSTOMER_PHONE = @NewCUSTOMER_PHONE " +
            "WHERE " +
            "CUSTOMER_FIRST_NAME = @CUSTOMER_FIRST_NAME, " +
            "CUSTOMER_LAST_NAME = @CUSTOMER_LAST_NAME, " +
            "CUSTOMER_STREET = @OldCUSTOMER_STREET, " +
            "CUSTOMER_STREET_NUMBER = @OldCUSTOMER_STREET_NUMBER" +
            "AND CUSTOMER_CITY = @OldCUSTOMER_CITY " +
            "AND CUSTOMER_STATE = @OldCUSTOMER_FIRST_NAME " +
            "AND CUSTOMER_FIRST_NAME = @OldCUSTOMER_FIRST_NAME;";
        MySql.Data.MySqlClient.MySqlCommand updateCommand =
            new MySql.Data.MySqlClient.MySqlCommand(updateStatement, connection);
        updateCommand.Parameters.AddWithValue(
            "@NewFirstName", newCustomer.FirstName);
        updateCommand.Parameters.AddWithValue(
           "@NewLastName", newCustomer.LastName);
        updateCommand.Parameters.AddWithValue(
            "@NewStreet", newCustomer.Street);
        updateCommand.Parameters.AddWithValue(
            "@NewStreetNumber", newCustomer.StreetNumber);
        updateCommand.Parameters.AddWithValue(
            "@CUSTOMER_CITY", newCustomer.City);
        updateCommand.Parameters.AddWithValue(
            "@CUSTOMER_STATE", newCustomer.State);
        updateCommand.Parameters.AddWithValue(
            "@NEW_PHONE", newCustomer.Phone);
        updateCommand.Parameters.AddWithValue(
           "@OldFirstName", oldCustomer.FirstName);
        updateCommand.Parameters.AddWithValue(
           "@OldLastName", oldCustomer.LastName);
        updateCommand.Parameters.AddWithValue(
           "@OldStreet", oldCustomer.Street);
        updateCommand.Parameters.AddWithValue(
            "@OldStreetNumber", oldCustomer.StreetNumber);
        updateCommand.Parameters.AddWithValue(
            "@OldCity", oldCustomer.City);
        updateCommand.Parameters.AddWithValue(
            "@OldState", oldCustomer.State);
        updateCommand.Parameters.AddWithValue(
            "@OldCUSTOMER_PHONE", oldCustomer.Phone);
        try
        {
            connection.Open();
            int count = updateCommand.ExecuteNonQuery();
            if (count > 0)
                return true;
            else
                return false;
        }
        catch (MySqlException ex)
        {
            throw ex;
        }
        finally
        {
            connection.Close();
        }

    }
}

publicstaticintaddcustomer（客户）
{
MySqlConnection=MySqlCommand.GetConnection（）；
字符串插入语句=
“插入客户（客户名、客户姓、客户城市、客户州、客户街道号码、客户街道、客户电话）”+
“值（@CUSTOMER\u FIRST\u NAME、@CUSTOMER\u LAST\u NAME、@CUSTOMER\u CITY、@CUSTOMER\u STATE、@CUSTOMER\u STREET\u NUMBER、@CUSTOMER\u STREET、@CUSTOMER\u PHONE）”；
MySql.Data.MySqlClient.MySqlCommand插入命令=
新的MySql.Data.MySqlClient.MySqlCommand（insertStatement，connection）；
insertCommand.Parameters.AddWithValue(
“@CUSTOMER\u FIRST\u NAME”，CUSTOMER.FirstName）；
insertCommand.Parameters.AddWithValue(
“@CUSTOMER\u LAST\u NAME”，CUSTOMER.LastName）；
insertCommand.Parameters.AddWithValue(
“@CUSTOMER_STREET_NUMBER”，CUSTOMER.STREET NUMBER）；
insertCommand.Parameters.AddWithValue(
“@CUSTOMER\u STREET\u NAME”，CUSTOMER.STREET）；
insertCommand.Parameters.AddWithValue(
“@CUSTOMER_CITY”，CUSTOMER.CITY）；
insertCommand.Parameters.AddWithValue(
“@CUSTOMER_STATE”，CUSTOMER.STATE）；
insertCommand.Parameters.AddWithValue(
“@CUSTOMER_PHONE”，CUSTOMER.PHONE）；
尝试
{
connection.Open（）；
insertCommand.ExecuteOnQuery（）；
字符串选择语句=
“从客户中选择最大值（客户ID）”；
MySql.Data.MySqlClient.MySqlCommand selectCommand=
新建MySql.Data.MySqlClient.MySqlCommand（selectStatement，connection）；
int customerID=Convert.ToInt32（selectCommand.ExecuteScalar（））；
返回客户ID；
}
捕获（MySqlException-ex）
{
掷骰子；
}
最后
{
connection.Close（）；
}
}
/// 
/// 
/// 
/// 
/// 
/// 
公共静态bool UpdateCustomer（客户oldCustomer，
客户（新客户）
{
MySqlConnection=MySqlCommand.GetConnection（）；
字符串更新语句=
“更新客户集”+
CUSTOMER\u FIRST\u NAME=@NewCUSTOMER\u FIRST\u NAME+
CUSTOMER\u LAST\u NAME=@NewCUSTOMER\u LAST\u NAME+
“客户街=@NewCUSTOMER街，”+
“客户街道号码=@V客户街道号码”+
客户城市=@NewCUSTOMER城市+
CUSTOMER\u STATE=@NewCUSTOMER\u STATE+
“客户电话=@NewCUSTOMER电话”+
“哪里”+
CUSTOMER\u FIRST\u NAME=@CUSTOMER\u FIRST\u NAME+
客户姓氏=@CUSTOMER\u LAST\u NAME+
“客户街=@OldCUSTOMER街，”+
“客户街号码=@OldCUSTOMER街号码”+
“和客户城市=@OldCUSTOMER城市”+
“和客户状态=@OldCUSTOMER\u FIRST\u NAME”+
“客户名=@OldCUSTOMER\u FIRST\u NAME；”；
MySql.Data.MySqlClient.MySqlCommand updateCommand=
新建MySql.Data.MySqlClient.MySqlCommand（updateStatement，connection）；
updateCommand.Parameters.AddWithValue(
“@NewFirstName”，newCustomer.FirstName）；
updateCommand.Parameters.AddWithValue(
“@NewLastName”，newCustomer.LastName）；
updateCommand.Parameters.AddWithValue(
“@NewStreet”，newCustomer.Street）；
updateCommand.Parameters.AddWithValue(
“@NewStreetNumber”，newCustomer.StreetNumber）；
updateCommand.Parameters.AddWithValue(
“@CUSTOMER_CITY”，newCustomer.CITY）；
updateCommand.Parameters.AddWithValue(
“@CUSTOMER\u STATE”，newCustomer.STATE）；
updateCommand.Parameters.AddWithValue(
“@NEW_PHONE”，newCustomer.PHONE）；
updateCommand.Parameters.AddWithValue(
“@OldFirstName”，oldCustomer.FirstName）；
updateCommand.Parameters.AddWithValue(
“@OldLastName”，oldCustomer.LastName）；
updateCommand.Parameters.AddWithValue(
“@OldStreet”，oldCustomer.Street）；
updateCommand.Parameters.AddWithValue(
“@OldStreetNumber”，oldCustomer.StreetNumber）；
updateCommand.Parameters.AddWithValue(
“@OldCity”，oldCustomer.City）；
updateCommand.Parameters.AddWithValue(
“@OldState”，oldCustomer.State）；
updateCommand.Parameters.AddWithValue(
“@OldCUSTOMER\u PHONE”，OldCUSTOMER.PHONE）；
尝试
{
connection.Open（）；
int count=updateCommand.ExecuteOnQuery（）；
如果（计数>0）
返回true；
其他的
返回false；
}
捕获（MySqlException-ex）
{
掷骰子；
}
最后
{
connection.Close（）；
}
}
}

}

---

我哪里做错了？我尝试了其他帖子中推荐的更改，但我没有看到任何运气。任何帮助都将不胜感激

尝试先插入，如果成功，则执行下一个查询：

public static int AddCustomer(Customer customer)
    {
        MySqlConnection connection = MySqlCommand.GetConnection();
        connection.Open();
        string insertStatement =
            "INSERT INTO customer (CUSTOMER_FIRST_NAME, CUSTOMER_LAST_NAME, CUSTOMER_CITY, CUSTOMER_STATE, CUSTOMER_STREET_NUMBER, CUSTOMER_STREET, CUSTOMER_PHONE) " +
            "VALUES (@CUSTOMER_FIRST_NAME, @CUSTOMER_LAST_NAME, @CUSTOMER_CITY, @CUSTOMER_STATE, @CUSTOMER_STREET_NUMBER, @CUSTOMER_STREET, @CUSTOMER_PHONE)";
        MySql.Data.MySqlClient.MySqlCommand insertCommand =
            new MySql.Data.MySqlClient.MySqlCommand(insertStatement, connection);
        insertCommand.Parameters.AddWithValue(
            "@CUSTOMER_FIRST_NAME", customer.FirstName);
        insertCommand.Parameters.AddWithValue(
           "@CUSTOMER_LAST_NAME", customer.LastName);
        insertCommand.Parameters.AddWithValue(
            "@CUSTOMER_STREET_NUMBER", customer.StreetNumber);
        insertCommand.Parameters.AddWithValue(
             "@CUSTOMER_STREET_NAME", customer.Street);
        insertCommand.Parameters.AddWithValue(
            "@CUSTOMER_CITY", customer.City);
        insertCommand.Parameters.AddWithValue(
            "@CUSTOMER_STATE", customer.State);
        insertCommand.Parameters.AddWithValue(
            "@CUSTOMER_PHONE", customer.Phone);
        insertCommand.ExecuteNonQuery();
        connection.Close();

替换：

发件人：

MySqlConnection connection = MySqlCommand.GetConnection();

MySqlConnection connection = new MySqlConnection("YourConnectionStringHere");

至：

MySqlConnection connection = MySqlCommand.GetConnection();

MySqlConnection connection = new MySqlConnection("YourConnectionStringHere");

---

它在更新或插入过程中失败了吗？在添加和更新功能过程中都失败了。您的错误到底是什么？@reds当我尝试在程序中运行添加或更新功能时，出现一个错误，读取“命令执行期间发生致命错误”。您的代码正在插入一条记录，并且在插入数据库后也将获得一条记录？但您只打开了一次连接，而没有关闭第一个连接。执行后是否插入了记录？