我使用下面列出的代码来处理被读入数据表的Excel表中的空单元格。

if (!reader.IsDBNull(2))
{
   row["Oracle"] = (string)reader[2];
}

此解决方案较少依赖于供应商，并与SQL, OleDB和MySQL Reader一起工作:

public static string GetStringSafe(this IDataReader reader, int colIndex)
{
    return GetStringSafe(reader, colIndex, string.Empty);
}

public static string GetStringSafe(this IDataReader reader, int colIndex, string defaultValue)
{
    if (!reader.IsDBNull(colIndex))
        return reader.GetString(colIndex);
    else
        return defaultValue;
}

public static string GetStringSafe(this IDataReader reader, string indexName)
{
    return GetStringSafe(reader, reader.GetOrdinal(indexName));
}

public static string GetStringSafe(this IDataReader reader, string indexName, string defaultValue)
{
    return GetStringSafe(reader, reader.GetOrdinal(indexName), defaultValue);
}

private static void Render(IList<ListData> list, IDataReader reader)
        {
            while (reader.Read())
            {

                listData.DownUrl = (reader.GetSchemaTable().Columns["DownUrl"] != null) ? Convert.ToString(reader["DownUrl"]) : null;
                //没有这一列时，让其等于null
                list.Add(listData);
            }
            reader.Close();
        }

下面是其他人可以根据@marc_s的答案使用的helper类:

public static class SQLDataReaderExtensions
    {
        public static int SafeGetInt(this SqlDataReader dataReader, string fieldName)
        {
            int fieldIndex = dataReader.GetOrdinal(fieldName);
            return dataReader.IsDBNull(fieldIndex) ? 0 : dataReader.GetInt32(fieldIndex);
        }

        public static int? SafeGetNullableInt(this SqlDataReader dataReader, string fieldName)
        {
            int fieldIndex = dataReader.GetOrdinal(fieldName);
            return dataReader.GetValue(fieldIndex) as int?;
        }

        public static string SafeGetString(this SqlDataReader dataReader, string fieldName)
        {
            int fieldIndex = dataReader.GetOrdinal(fieldName);
            return dataReader.IsDBNull(fieldIndex) ? string.Empty : dataReader.GetString(fieldIndex);
        }

        public static DateTime? SafeGetNullableDateTime(this SqlDataReader dataReader, string fieldName)
        {
            int fieldIndex = dataReader.GetOrdinal(fieldName);
            return dataReader.GetValue(fieldIndex) as DateTime?;
        }

        public static bool SafeGetBoolean(this SqlDataReader dataReader, string fieldName)
        {
            return SafeGetBoolean(dataReader, fieldName, false);
        }

        public static bool SafeGetBoolean(this SqlDataReader dataReader, string fieldName, bool defaultValue)
        {
            int fieldIndex = dataReader.GetOrdinal(fieldName);
            return dataReader.IsDBNull(fieldIndex) ? defaultValue : dataReader.GetBoolean(fieldIndex);
        }
    }

整洁的小笑话:

    while (dataReader.Read())
{
    employee.FirstName = (!dataReader.IsDBNull(dataReader.GetOrdinal("FirstName"))) ? dataReader["FirstName"].ToString() : "";
}

如何创建帮助方法

为字符串

private static string MyStringConverter(object o)
    {
        if (o == DBNull.Value || o == null)
            return "";

        return o.ToString();
    }

使用

MyStringConverter(read["indexStringValue"])

为整数

 private static int MyIntonverter(object o)
    {
        if (o == DBNull.Value || o == null)
            return 0;

        return Convert.ToInt32(o);
    }

使用

MyIntonverter(read["indexIntValue"])

为日期

private static DateTime? MyDateConverter(object o)
    {
        return (o == DBNull.Value || o == null) ? (DateTime?)null : Convert.ToDateTime(o);
    }

使用

MyDateConverter(read["indexDateValue"])

注意:对于DateTime声明变量为

DateTime? variable;