为什么在ASP.NET中重新加载页面时会运行按钮事件函数?

public partial class Stats : System.Web.UI.Page
{
    public SqlDataReader DataReader;
    public SqlCommand Command;
    string queryString = ("INSERT INTO UserData (UserProfileID, ConfidenceLevel, LoveLevel, HappinessLevel) VALUES ('a051fc1b-4f51-485b-a07d-0f378528974e', 1, 1, 1);");

    protected void Page_Load(object sender, EventArgs e)
    {
       LabelUserID.Text = Membership.GetUser().ProviderUserKey.ToString();
    }

    protected void Button1_Click(object sender, EventArgs e)
    {
        MySqlConnection database = new MySqlConnection();
        database.CreateConn();

        Command = new SqlCommand(queryString, database.Connection);
        Command.ExecuteNonQuery();        
    }
}

Button1_Click() 正在重新加载页上执行。