CommandText属性初始化问题

Question

我正在尝试使用 C# 控制台应用程序同时将数据实现到 2 个（后来是 3 个）表中。我想在表“用户”中实现名字、姓氏和用户ID，用户ID将自动递增。

同样的 userID 也应该与 porilfeID（再次通过自动增量自动完成）和 profileName 一起实现到表“profile”中。

但在某个地方它会抛出命令文本未正确初始化的错误，我无法再弄清楚我做错了什么。

class SQLCreate
{
    public void create(int entries)
    {
        string ConnectionString = "server=localhost;uid=root;pwd=;database=databaseassignment;";

        MySqlConnection conn;
        MySqlCommand cmd;
        MySqlDataAdapter adapter;

        conn = new MySqlConnection();

        int entryValue = entries;
        conn.ConnectionString = ConnectionString;

        try
        {
            Stopwatch stopw = new Stopwatch();
            stopw.Start();
            conn.Open();

            cmd = new MySqlCommand();
            adapter = new MySqlDataAdapter();

            cmd.Connection = conn;

            for (int i = 0; i < entryValue; i++)
            {
          
                MySqlCommand cmd1 = new MySqlCommand("INSERT INTO user (firstName, lastName) VALUES (@firstName, @lastName)", conn);
                //MySqlCommand cmd1 = new MySqlCommand("INSERT INTO user (firstName, lastName) VALUES (@firstName, @lastName)", conn);
    
    
                cmd1.Parameters.AddWithValue("@firstName", "John");
                cmd1.Parameters.AddWithValue("@lastName", "Doe");
    
                cmd1.CommandType = CommandType.Text;
    
                int userId = Convert.ToInt32(cmd1.ExecuteScalar());
    
                MySqlCommand cmd2 = new MySqlCommand("INSERT INTO profile (userId, profileName) VALUES (@userId, @profileName)", conn);
    
                cmd2.Parameters.AddWithValue("@userId", userId);
                cmd2.Parameters.AddWithValue("@profileName", "John Doe");
                    
                cmd2.CommandType = CommandType.Text;
    
                cmd2.ExecuteNonQuery();
    
                string firstName = Faker.Name.First();
                string lastName = Faker.Name.Last();
                string profileName = Faker.Name.First();
    
                cmd.Parameters.Add("@firstName", MySqlDbType.String);
                cmd.Parameters["@firstName"].Value = firstName;
    
                cmd.Parameters.Add("@lastName", MySqlDbType.String);
                cmd.Parameters["@lastName"].Value = lastName;
    
                cmd.Parameters.Add("@profileName", MySqlDbType.String);
                cmd.Parameters["@profileName"].Value = profileName;
    
                cmd.ExecuteNonQuery();
            }
            conn.Close();
            stopw.Stop();
            Console.WriteLine(" Time elapsed: {0} ", stopw.Elapsed);
        } catch (MySql.Data.MySqlClient.MySqlException ex) {
            Console.WriteLine(ex.Message);
        }
    }
}
}

Answer 1

您创建 cmd = new MySqlCommand(); 但从未设置其 .CommandText 属性。调用 cmd.ExecuteNonQuery(); 将失败，因为没有 CommandText 可以执行。

设置 cmd.CommandText 或将构造函数更改为 cmd = new MySqlCommand("text here", conn);。