ASP.net数据库查询，急…… - .NET技术 / ASP.NET

protected void btnEnter1_Click(object sender, EventArgs e)
  {
  string username = txtUserName.Text.Trim();
  string strConnection = "Data Source=.;Initial Catalog=MySchool;User ID=sa;Password=guo";
  string strSql = "select * from Student where LoginId='@username'";
  SqlConnection conn = new SqlConnection(strConnection);
  SqlCommand command = new SqlCommand();
  command.CommandText = strSql;
  command.Connection = conn;
  SqlParameter param = new SqlParameter("@username", SqlDbType.VarChar, 30);
  param.Value = username;
  command.Parameters.Add(param);//添加参数
  conn.Open();
  SqlDataReader reader= command.ExecuteReader();
  GridView2.DataSource = reader;
  GridView2.DataBind();//进行数据绑定
  reader.Close();
  conn.Close();
  conn.Dispose();
  }为啥老是不出结果，请各位帮忙看看！

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SQL code:

改成我这样就好了
protected void btnEnter1_Click(object sender, EventArgs e)
{
string username = txtUserName.Text.Trim();
string strConnection = "server=.;database=MySchool;uid=sa;pwd=guo";
string strSql = &