Reader Dataset Parameter

Of course,perhaps the most important parameter is that which defines the dataset to be read.在导航器窗口中也可以找到：

像往常一样，double-clicking the parameter opens a dialog for it to be changed.You can change the dataset being read by selecting any other dataset - of the same format - within that dialog.

Multiple Dataset Selection

As long as the format is file-based (i.e.not a database) a Reader is capable of reading multiple source datasets:

要做到这一点，when selecting the dataset to read simply select multiple files instead of a single one.

小费

When selecting a source dataset,an advanced file browser is available.This allows you to select files from different folders,all at the same time!

文件数据集类型

When dealing with files it's useful to consider datasets as existing in two differnt forms: File-based and Folder-based

File-Based Datasets

基于文件的数据集就是：一个包含所有数据层的单一文件。A format of this type has an internal structure that assigns data to different layers within the file.

Good examples of this are:

• AutoCAD DWG: Each DWG file is a dataset containing its own set of layers
• Microsoft Excel: Each Excel file is a dataset containing a set of sheets

In this scenario the dataset parameter is simply a pointer to the location of the file(s),here a single AutoCAD dataset:

Folder-Based Datasets

A folder-based dataset is still made up of files (of course).However,此类型的格式没有定义层的内部方法。Therefore each layer becomes a separate file within a folder.

Good examples of this are:

• Esri Shapefile: To store different layers requires multiple Shapefiles: e.g.roads.shp and railways.shp
• 逗号分隔（csv）: To store separate tables requires two separate CSV files

在这个场景中，dataset参数是指向单个文件的指针，here a set of layers in a shapefile dataset: