/// <summary>
/// 返回一个单独值
/// </summary>
/// <param name="strSQL">查询语句</param>
/// <returns>SQL语句结果，单值。</returns>
public string GetDBValue_ex(string strSQL)
{
string ret="";
SqlConnection oConn=DBCreateCN();
SqlCommand oCmd=new SqlCommand(strSQL,oConn);
ret=Convert.ToString(oCmd.ExecuteScalar());
oConn.Close();
return ret;
}