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Inferring Tables

  • Bài viết

When inferring a schema for a DataSet from an XML document, ADO.NET first determines which XML elements represent tables. The following XML structures result in a table for the DataSet schema:

  • Elements with attributes

  • Elements with child elements

  • Repeating elements

Elements with Attributes

Elements that have attributes specified in them result in inferred tables. For example, consider the following XML:

<DocumentElement>  
  <Element1 attr1="value1"/>  
  <Element1 attr1="value2">Text1</Element1>  
</DocumentElement>

The inference process produces a table named "Element1."

DataSet: DocumentElement

Table: Element1

attr1 Element1_Text
value1
value2 Text1

Elements with Child Elements

Elements that have child elements result in inferred tables. For example, consider the following XML:

<DocumentElement>  
  <Element1>  
    <ChildElement1>Text1</ChildElement1>  
  </Element1>  
</DocumentElement>

The inference process produces a table named "Element1."

DataSet: DocumentElement

Table: Element1

ChildElement1
Text1

The document, or root, element result in an inferred table if it has attributes or child elements that are inferred as columns. If the document element has no attributes and no child elements that would be inferred as columns, the element is inferred as a DataSet. For example, consider the following XML:

<DocumentElement>  
  <Element1>Text1</Element1>  
  <Element2>Text2</Element2>  
</DocumentElement>

The inference process produces a table named "DocumentElement."

DataSet: NewDataSet

Table: DocumentElement

Element1 Element2
Text1 Text2

Alternatively, consider the following XML:

<DocumentElement>  
  <Element1 attr1="value1" attr2="value2"/>  
</DocumentElement>

The inference process produces a DataSet named "DocumentElement" that contains a table named "Element1."

DataSet: DocumentElement

Table: Element1

attr1 attr2
value1 value2

Repeating Elements

Elements that repeat result in a single inferred table. For example, consider the following XML:

<DocumentElement>  
  <Element1>Text1</Element1>  
  <Element1>Text2</Element1>  
</DocumentElement>

The inference process produces a table named "Element1."

DataSet: DocumentElement

Table: Element1

Element1_Text
Text1
Text2

See also