Second, the XML driver determines which columns are in a specific table. An _ID column, which is essentially a primary key, is automatically generated for each table. If a table is determined to be a child of another table, then it is given a second generated column. The name of this column is prefixed with the parent table’s name and ends with
_ID, for example,
_purchaseOrder_ID.
Consider the previous example document. The items table will receive two generated columns, _ID and _
purchaseOrder_ID, which are assigned an integer data type. The purchaseOrder table receives only the
_ID column, because it does not have a parent table.