C# Access 读写数据库 UPDATE无效 是什么问题？

做查询时候，是可以执行并返回数据的。

protected void Button1_Click(object sender, EventArgs e)
{
    string str = "Provider=Microsoft.ACE.OLEDB.12.0;Data Source=F:/Public/access/kq.accdb";
    String str1 = gh0.Text;
    String str2 = rq0.Text;
    OleDbConnection OleDbConnection = new OleDbConnection(str);
    OleDbConnection.Open();
    OleDbCommand sqlcmd = new OleDbCommand(@"SELECT  rq,gh,bm,zw,xm,gs,psjb,zmjb,jjrjb,shij,bingj,kg,hunj,chanj,peicj,sangj,gongs,nianj,texiu,wdk,sjss FROM no1  WHERE gh='" + str1 + "' and rq='" + str2 + "'  ", OleDbConnection);
    OleDbDataReader reader = sqlcmd.ExecuteReader();
    if (reader.Read())
    {
        rq.Text = reader["rq"].ToString();
        gh.Text = reader["gh"].ToString();
        bm.Text = reader["bm"].ToString();
        zw.Text = reader["zw"].ToString();
        xm.Text = reader["xm"].ToString();
        gs.Text = reader["gs"].ToString();
        psjb.Text = reader["psjb"].ToString();
        zmjb.Text = reader["zmjb"].ToString();
        jjrjb.Text = reader["jjrjb"].ToString();
        shij.Text = reader["shij"].ToString();
        bingj.Text = reader["bingj"].ToString();
        kg.Text = reader["kg"].ToString();
        hunj.Text = reader["hunj"].ToString();
        chanj.Text = reader["chanj"].ToString();
        peicj.Text = reader["peicj"].ToString();
        sangj.Text = reader["sangj"].ToString();
        gongs.Text = reader["gongs"].ToString();
        nianj.Text = reader["nianj"].ToString();
        texiu.Text = reader["texiu"].ToString();
        wdk.Text = reader["wdk"].ToString();
        sjss.Text = reader["sjss"].ToString();
    }
    else
    {
    }
}

做UPDATE的时候没有反应，是哪边出了问题。

protected void Button2_Click(object sender, EventArgs e)
{
    string str = "Provider=Microsoft.ACE.OLEDB.12.0;Data Source=F:/Public/access/kq.accdb";
    String str1 = gh0.Text;
    String str2 = rq0.Text;
    OleDbConnection OleDbConnection = new OleDbConnection(str);
    OleDbConnection.Open();
    OleDbCommand sqlcmd = new OleDbCommand(@"UPDATE no1 SET  gs = '66'    WHERE gh='" + str1 + "' and rq='" + str2 + "'   ", OleDbConnection);
    sqlcmd.ExecuteNonQuery();

}

如果执行出错，会丢出异常，没有异常说明要么没有执行，要么更新了，但是更新的不是你期望的数据，导致你没看到变化，要么是更新的数据库不是你打开看的那个数据库文件