MSAccess数据库更新不使用c#进行更新

I am making a database system. I've implemented the INSERT function properly but when I tried implementing the UPDATE function, I couldn't make any changes to the database. I don;t know where I went wrong.
Note: username is declared as string

我正在做一个数据库系统。我已经正确地实现了INSERT函数，但是当我尝试实现UPDATE函数时，我无法对数据库做任何更改。我不知道哪里出错了。注意:用户名被声明为字符串

Here is the function handling the UPDATE:

下面是处理更新的函数:

private void btnUpdate_Click(object sender, EventArgs e)
    {

        string q = "UPDATE [registrationinfo] SET [Password]='?', [EmailAdd]='?', [HomeAdd]='?' WHERE [Username]='?'";

        OleDbConnection connect = new OleDbConnection(MyConnectionString);
        connect.Open();
        try
        {
            OleDbCommand command = new OleDbCommand(q,connect);

            command.Parameters.AddWithValue("@Password", txt_password.Text);
            command.Parameters.AddWithValue("@EmailAdd", txt_eadd.Text);
            command.Parameters.AddWithValue("@HomeAdd", txt_homeadd.Text);
            command.Parameters.AddWithValue("Username", username);

            command.ExecuteNonQuery();

            txt_password.Clear();
            txt_eadd.Clear();
            txt_homeadd.Clear();
            txt_conPass.Clear();
        }
        catch (Exception ex)
        {
            connect.Close();
            MessageBox.Show(ex.Message.ToString());
        }

        connect.Close();            
    }

1 个解决方案

#1

When using a parameterized query you do not need to put single quotes (') around text parameters in your CommandText, so you should be using something like this:

当使用参数化查询时，您不需要在CommandText中为文本参数设置单引号，因此您应该使用以下方法:

string q = "UPDATE [registrationinfo] SET [Password]=?, [EmailAdd]=?, [HomeAdd]=? WHERE [Username]=?";