Summary of the DataSet Schema Inference Process

 

The inference process first determines, from the XML document, which elements will be inferred as tables. From the remaining XML, the inference process determines the columns for those tables. For nested tables, the inference process generates nested DataRelation and ForeignKeyConstraint objects.

Following is a brief summary of inference rules:

  • Elements that have attributes are inferred as tables.

  • Elements that have child elements are inferred as tables.

  • Elements that repeat are inferred as a single table.

  • If the document, or root, element has no attributes, and no child elements that would be inferred as columns, it is inferred as a DataSet. Otherwise, the document element is inferred as a table.

  • Attributes are inferred as columns.

  • Elements that have no attributes or child elements, and that do not repeat, are inferred as columns.

  • For elements that are inferred as nested tables within other elements that are also inferred as tables, a nested DataRelation is created between the two tables. A new, primary key column named TableName_Id is added to both tables and used by the DataRelation. A ForeignKeyConstraint is created between the two tables using the TableName_Id column.

  • For elements that are inferred as tables and that contain text but have no child elements, a new column named TableName_Text is created for the text of each of the elements. If an element is inferred as a table and has text, but also has child elements, the text is ignored.

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