在ACCESS中取日期类型的值怎么取，请求帮忙

在ACCESS中取出相符条件的日期类型的值，然后只要一条，让当前年月和取出得值进行比较如果年月相等执行修改操作，如果年月不相等执行插入操作，我写的代码为什么执行到定义数据里时间的时候，直接跳转到放弃执行那一段代码了？高手帮忙看看，指点下
public void ProcessRequest (HttpContext context) {
context.Response.ContentType = "text/plain";
if (context.Request.QueryString["score"] != null&&context .Request.QueryString["empid"]!=null)
{
try
{

string strconn = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=" +context.Server.MapPath("~/App_Data/db.mdb");
OleDbConnection mycon = new OleDbConnection(strconn);
mycon.Open();
string[] strscore = context.Request.QueryString["score"].ToString().Split(',');
string strSelect = "select khtime from khresult where empid = '" + context.Request.QueryString["empid"] + "' order by khtime desc";
OleDbCommand cmd = new OleDbCommand(strSelect, mycon);
//int timeLast = Convert.ToInt32(cmd.ExecuteScalar()) ;
DateTime LastTime = Convert.ToDateTime(cmd.ExecuteScalar().ToString());
int year = DateTime.Now.Year-LastTime.Year ;
int month =DateTime.Now.Month - LastTime.Month ;
int flag=-1;
if (year != 0)
{
flag = 1;

}
else if (month >= 1)
{
flag = 1;
}
else flag = 0;

foreach (string score in strscore)
{
if (score.Trim() != "")
{

if (flag == 1)
{
string strinsert = "insert into khresult(empid,khbh1,khfs1,khtime) values(" + context.Request.QueryString["empid"] + "," + score.Split('|')[1] + ",'" + score.Split('|')[0] + "','" + DateTime.Now + "')";
cmd.CommandText = strinsert;
cmd.ExecuteNonQuery();
}
else
{
string strSql = "update khresult set khfs1 = '" + score.Split('|')[0]+"',khtime = '" + DateTime.Now +"' where empid = '" +context.Request.QueryString["empid"]+
" and khbh1 ="+score.Split('|')[1];
}
}
}
mycon.Close();
context.Response.Write("success");
}
catch
{
context.Response.Write("failure");
}
}
}
执行到 DateTime LastTime = Convert.ToDateTime(cmd.ExecuteScalar().ToString());
直接跳转到catch了，后面都不执行了，郁闷

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你cmd.ExecuteScalar() 肯定不是一个时间灶芹啊，
你先把时间取出来，大散再 DateTime LastTime = Convert.ToDateTime（滚辩氏时间）；

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