Question

我不知道为什么会收到此错误：

C＃代码：

using (MySqlConnection connection = new MySqlConnection("datasource=localhost;port=3306;database=project;username=***;password=***;"))
{
MySqlCommand cmd = new MySqlCommand("INSERT INTO student (studentID, studentFirstName, studentLastName, studentUserName, studentPassword) VALUES (@userID, @, @FirstName, @LastName, @Username, @Password);");
cmd.CommandType = CommandType.Text;
cmd.Connection = connection;
cmd.Parameters.AddWithValue("userID", Convert.ToInt32(textBoxUserID.Text));
cmd.Parameters.AddWithValue("@FirstName", textBoxFirstName.Text);
cmd.Parameters.AddWithValue("@LastName", textBoxLastName.Text);
cmd.Parameters.AddWithValue("@UserName", textBoxUsername.Text);
cmd.Parameters.AddWithValue("@Password", textBoxPassword.Text);
connection.Open();
cmd.Connection = connection;
cmd.ExecuteNonQuery();
MessageBox.Show("Saved");
connection.Close();
}

可能是因为我忽视了某些事情。

错误：

未处理的类型＆＃39; MySql.Data.MySqlClient.MySqlException＆＃39;发生在MySql.Data
中
附加信息：列数与第1行的值计数不匹配

Answer 1

格式化您的代码，您将清楚地看到所有语法问题：

string connectionString = 
  "datasource=localhost;port=3306;database=project;username=***;password=***;";

using (MySqlConnection connection = new MySqlConnection(connectionString)) {
  connection.Open();

  //DONE: keep sql readable
  string sql = 
    @"INSERT INTO student (
         studentID, 
         studentFirstName, 
         studentLastName, 
         studentUserName, 
         studentPassword) 
      VALUES (
         @userID, 
         @FirstName, -- wrong @ param 
         @LastName, 
         @Username, 
         @Password);";

  //DONE: wrap IDisposable into using
  using (MySqlCommand cmd = new MySqlCommand(sql)) {
    cmd.CommandType = CommandType.Text; // redundant
    cmd.Connection = connection;

    //DONE: separate code with new lines
    // wrong parameter name
    cmd.Parameters.AddWithValue("@userID", Convert.ToInt32(textBoxUserID.Text));
    cmd.Parameters.AddWithValue("@FirstName", textBoxFirstName.Text);
    cmd.Parameters.AddWithValue("@LastName", textBoxLastName.Text);
    cmd.Parameters.AddWithValue("@UserName", textBoxUsername.Text);
    cmd.Parameters.AddWithValue("@Password", textBoxPassword.Text);

    cmd.ExecuteNonQuery();
  } 
}

MessageBox.Show("Saved");

Answer 2

您在值子句中添加了一个附加参数（@ userID， @ ，

还要添加＆＃34; @＆＃34;在用户ID之前

cmd.Parameters.AddWithValue("userID", Convert.ToInt32(textBoxUserID.Text));

应该是

cmd.Parameters.AddWithValue("@userID", Convert.ToInt32(textBoxUserID.Text));

列数与第1行的值计数匹配＃

2 个答案: