Gets or sets a value indicating whether empty string values are converted to a null reference nothing in visual basic when the field values are returned from the data source 获取或设置一个值，用于指示在从数据源返回字段值时，空字符串( " )值是否转换为空引用（在visual basic中为nothing ） 。
In scalar context , returns the number of fields found and splits into the @ _ array . use of split in scalar context is deprecated , however , because it clobbers your subroutine arguments 在标量上下文，返回字段的个数并且将列表放到默认数组@ _ .但是这是不可取的，因为它可能会影响子程序的参数。
