c#中oracle的to_date函数使用方法

public static DataTable Query()

{

  const string sSql = "select xh,lsh,name from table where gxsj>to_date(:gxsj,'yyyy-MM-dd HH24:mi:ss')";

  OracleParameter[] parameters = {new OracleParameter(":gxsj", OracleType.VarChar, 10)};

  parameters[0].Value = DateTime.Now.AddHours(-3).ToString("yyyy-MM-dd HH") + ":00:00";

  return DBUtility.DbHelperOra.Query(sSql, parameters).Tables[0];

}

public static string GetHphm(string sClsbdh)
{
  const string sSql = "select name from table where sj>to_date(:yxsj,'yyyy-MM-dd')";
  OracleParameter[] paramters = {new OracleParameter("sj", OracleType.VarChar, 10)};
  paramters[0].Value = DateTime.Now.ToString("yyyy-MM-dd");
 
  using (var mReader = DbHelperOra.ExecuteReader(sSql, paramters))
  {
      if (mReader.Read())
      {
      return mReader["name"].ToString();
      }
  }
 
  return "";
}