要修复'The ConnectionString property has not been initialized.'

Question

我当前正在遇到错误：System.InvalidoperationException："连接属性尚未初始化"。当我试图将数据从C＃表单（多个文本框）输入到SQL数据库表单时，我想帮助解决此问题。

 private void AcceptData()
    {
        using (Connection = new SqlConnection(connectionString))
        using (SqlDataAdapter adapter = new SqlDataAdapter("INPUT INTO Person", Connection))//, Connection
        {
            DataTable RegisterTable = new DataTable();
            adapter.Fill(RegisterTable); //System.InvalidOperationException: 'The ConnectionString property has not been initialized.' TO FIX
            string name = textBox1.Text;
            string organisation = textBox3.Text;
            DateTime Time = DateTime.Parse(textBox2.Text);
            string strDateTimeIn = Time.ToString("yyyy-MM-dd HH:mm:ss.ffff");
            string query = "INSERT INTO Person (Name,Organisation,TimeIn) VALUES('" + name + "','" + organisation + "','" +strDateTimeIn+ "')";
            SqlCommand SignIn = new SqlCommand(query,Connection);
            SignIn.ExecuteNonQuery();
        }
    }

任何帮助将不胜感激

使用的连接字符串是：string connectionString = (@"Data Source=(LocalDB)MSSQLLocalDB;AttachDbFilename=|DataDirectory|Register.mdf;Integrated Security=True");

Answer 1

您需要打开连接

using (Connection = new SqlConnection(connectionString))
{
    connection.Open();
    using (SqlDataAdapter adapter = new SqlDataAdapter("INPUT INTO Person", Connection))//, Connection
        {
            DataTable RegisterTable = new DataTable();
            adapter.Fill(RegisterTable); //System.InvalidOperationException: 'The ConnectionString property has not been initialized.' TO FIX
            string name = textBox1.Text;
            string organisation = textBox3.Text;
            DateTime Time = DateTime.Parse(textBox2.Text);
            string strDateTimeIn = Time.ToString("yyyy-MM-dd HH:mm:ss.ffff");
            string query = "INSERT INTO Person (Name,Organisation,TimeIn) VALUES('" + name + "','" + organisation + "','" +strDateTimeIn+ "')";
            SqlCommand SignIn = new SqlCommand(query,Connection);
            SignIn.ExecuteNonQuery();
        }
}

Answer 2

"连接属性尚未初始化" 清楚地表明，打开SqlConnection的连接字符串属性在该方法内未正确分配。要解决此问题，要么在方法主体中分配连接字符串：

private void AcceptData()
{
    // assumed the connection string obtained from app.config or web.config file
    string connectionString = ConfigurationManager.ConnectionStrings["ConnectionStringName"].ConnectionString;
    using (SqlConnection Connection = new SqlConnection(connectionString))
    {
        Connection.Open(); // open the connection before using adapter
        using (SqlDataAdapter adapter = new SqlDataAdapter("INPUT INTO Person", Connection))
        {
            // other stuff
        }
    }
    // other stuff
}

或将连接字符串作为方法参数传递：

private void AcceptData(string connectionString)
{
    using (SqlConnection Connection = new SqlConnection(connectionString))
    {
        Connection.Open(); // open the connection before using adapter
        using (SqlDataAdapter adapter = new SqlDataAdapter("INPUT INTO Person", Connection))
        {
            // other stuff
        }
    }
    // other stuff
}

参考：

如何修复" ConnectionString属性"尚未初始化

c＃数据库连接属性尚未初始化