conn.Open(); OleDbDataAdapter adapter = new OleDbDataAdapter("SELECT sum_count, pass_count, fail_count FROM test_result", conn); DataTable dt = new DataTable(); adapter.Fill(dt); conn.Close(); if (dt.Rows.Count > 0) { totalCount = Convert.ToInt32(dt.Rows[0]["sum_count"]); okCount = Convert.ToInt32(dt.Rows[0]["pass_count"]); ngCount = Convert.ToInt32(dt.Rows[0]["fail_count"]); double passRate = (double)okCount / totalCount; txt_passrate.Text = passRate.ToString("P2"); //passRate = Convert.ToInt32(dt.Rows[0]["pass_rate"]); txt_sumcount.Text = " " + totalCount.ToString(); txt_passcount.Text = " " + okCount.ToString(); txt_failcount.Text = " " + ngCount.ToString(); //txt_passrate.Text = " " + passRate.ToString(); },以上代码中，当okcount,ngcount,totalcount数据都清零时，下次打开软件，txt_passrate.Text组件显示NAN，怎么让它显示0%

可以在计算通过率之前，检查 `totalCount` 是否为零，如果为零，则直接将通过率设置为0，如下所示：

if (dt.Rows.Count > 0) {
    totalCount = Convert.ToInt32(dt.Rows[0]["sum_count"]);
    okCount = Convert.ToInt32(dt.Rows[0]["pass_count"]);
    ngCount = Convert.ToInt32(dt.Rows[0]["fail_count"]);

    if (totalCount == 0) {
        txt_passrate.Text = "0%";
    } else {
        double passRate = (double)okCount / totalCount;
        txt_passrate.Text = passRate.ToString("P2");
    }

    txt_sumcount.Text = " " + totalCount.ToString();
    txt_passcount.Text = " " + okCount.ToString();
    txt_failcount.Text = " " + ngCount.ToString();
}

这样，当 `totalCount` 为零时，就会直接将 `txt_passrate.Text` 设置为 "0%"。