"Bill C." <billybobc1210@yahoo.com> wrote in message
news:1e75a833.0311210833.14494667@posting.google.com...
> Hi,
>
> I've got a simple console app that just reads an XML file into a DataSet
> then prints out a description of each table in the DataSet, including
> column names and row values for each column. I'm getting some strange
> results depending the input XML file I use. I was wondering if somebody
> could help me understand what is going on or point me to a good reference.
>
> The code for my program looks like this:
>
> using System;
> using System.Data;
>
> static void Main(string[] args)
> {
> DataSet ds = new DataSet();
> ds.ReadXml("test.xml");
> PrintDataSet(ds);
> }
>
> public static void PrintDataSet(DataSet ds)
> {
> Console.WriteLine("DataSet name: " + ds.DataSetName);
> foreach (DataTable dt in ds.Tables)
> {
> int rowCount = dt.Rows.Count;
> Console.WriteLine("\nTable: " + dt.ToString() + " (" + rowCount +
" rows)");
> foreach (DataColumn dc in dt.Columns)
> {
> Console.WriteLine("Column: " + dc.ColumnName);
> for (int i = 0; i < rowCount; i++)
> {
> Console.WriteLine("Row " + i + ": " +
dt.Rows[i][dc].ToString());
> }
> }
> }
> }
>
> When "test.xml" looks like this:
>
> <?xml version="1.0" standalone="yes"?>
> <test>
> <product>Product 1</product>
> <customer>
> <name>Bill</name>
> <company>Bill's Co.</company>
> </customer>
> <customer>
> <name>Sue</name>
> <company>Sue's Co.</company>
> </customer>
> </test>
>
> The output looks like this:
>
> DataSet name: NewDataSet
>
> Table: test (1 rows)
> Column: product
> Row 0: Product 1
> Column: test_Id
> Row 0: 0
>
> Table: customer (2 rows)
> Column: name
> Row 0: Bill
> Row 1: Sue
> Column: company
> Row 0: Bill's Co.
> Row 1: Sue's Co.
> Column: test_Id
> Row 0: 0
> Row 1: 0
>
> However when "test.xml" looks like this (NOTE: the only difference
> is in the <product> element):
>
> <?xml version="1.0" standalone="yes"?>
> <test>
> <product>
> <name>Product 1</name>
> </product>
> <customer>
> <name>Bill</name>
> <company>Bill's Co.</company>
> </customer>
> <customer>
> <name>Sue</name>
> <company>Sue's Co.</company>
> </customer>
> </test>
>
> The output looks like this:
>
> DataSet name: test
>
> Table: product (1 rows)
> Column: name
> Row 0: Product 1
>
> Table: customer (2 rows)
> Column: name
> Row 0: Bill
> Row 1: Sue
> Column: company
> Row 0: Bill's Co.
> Row 1: Sue's Co.
>
> Questions:
>
> 1) I think I see why the test_Id column gets created "on the fly" for
> the "customer" table in the first XML example. A "test" table got
> created which might have multiple rows. So each row of the "customer"
> table has to have some way of relating back to its parent table row,
> which is what "test_Id" contains. But why does the "test" table
> itself need a "test_Id" column?
>
> 2) In the first example a "test" table got created and the name of the
> DataSet stayed at the default "NewDataSet". In the second example there
> was no "test" table created. Instead the name of the DataSet is "test"
> and there is a "product" table and "customer" table. Since there is no
> "test" table there is no need for the "test_Id" column in any of the
> tables that do exist. Why does it work this way? Why would just changing
> that one element (ie. <product>) make such a big difference in the way the
> way the DataSet is constructed.
>
> Any help appreciated. And again if you know of some good reference books
> or links where these issues are discussed that would be fantastic.
>
> Thanks in advance.
>
> Bill

"Chris Lovett" <chris@!nospam!.net> wrote in message news:<vru5dpi0l063cf@corp.supernews.com>...
> XML is hierarchical. DataSet is not. So there are some "hieristics" that
> are used to "normalize" the XML into a relational shape. One of those
> hieristics is that if an element contains children then it is mapped to a
> table, just in case those children are repeated somewhere.
>
> You can make the DataSet behave much more predictably by providing it with
> an XML Schema. To see how this is done call WriteXml with
> XmlWriteMode.WriteSchema. Then be sure to read this file back in using
> XmlReadMode.ReadSchema.
>
> You are using XmlReadMode.InferSchema which is one of those "let's help
> people get started" kinds of features. Not really something you should use
> in a "production" application.
>
>
> "Bill C." <billybobc1210@yahoo.com> wrote in message
> news:1e75a833.0311210833.14494667@posting.google.com...
> > Hi,
> >
> > I've got a simple console app that just reads an XML file into a DataSet
> > then prints out a description of each table in the DataSet, including
> > column names and row values for each column. I'm getting some strange
> > results depending the input XML file I use. I was wondering if somebody
> > could help me understand what is going on or point me to a good reference.
> >
> > The code for my program looks like this:
> >
> > using System;
> > using System.Data;
> >
> > static void Main(string[] args)
> > {
> > DataSet ds = new DataSet();
> > ds.ReadXml("test.xml");
> > PrintDataSet(ds);
> > }
> >
> > public static void PrintDataSet(DataSet ds)
> > {
> > Console.WriteLine("DataSet name: " + ds.DataSetName);
> > foreach (DataTable dt in ds.Tables)
> > {
> > int rowCount = dt.Rows.Count;
> > Console.WriteLine("\nTable: " + dt.ToString() + " (" + rowCount +
> " rows)");
> > foreach (DataColumn dc in dt.Columns)
> > {
> > Console.WriteLine("Column: " + dc.ColumnName);
> > for (int i = 0; i < rowCount; i++)
> > {
> > Console.WriteLine("Row " + i + ": " +
> dt.Rows[i][dc].ToString());
> > }
> > }
> > }
> > }
> >
> > When "test.xml" looks like this:
> >
> > <?xml version="1.0" standalone="yes"?>
> > <test>
> > <product>Product 1</product>
> > <customer>
> > <name>Bill</name>
> > <company>Bill's Co.</company>
> > </customer>
> > <customer>
> > <name>Sue</name>
> > <company>Sue's Co.</company>
> > </customer>
> > </test>
> >
> > The output looks like this:
> >
> > DataSet name: NewDataSet
> >
> > Table: test (1 rows)
> > Column: product
> > Row 0: Product 1
> > Column: test_Id
> > Row 0: 0
> >
> > Table: customer (2 rows)
> > Column: name
> > Row 0: Bill
> > Row 1: Sue
> > Column: company
> > Row 0: Bill's Co.
> > Row 1: Sue's Co.
> > Column: test_Id
> > Row 0: 0
> > Row 1: 0
> >
> > However when "test.xml" looks like this (NOTE: the only difference
> > is in the <product> element):
> >
> > <?xml version="1.0" standalone="yes"?>
> > <test>
> > <product>
> > <name>Product 1</name>
> > </product>
> > <customer>
> > <name>Bill</name>
> > <company>Bill's Co.</company>
> > </customer>
> > <customer>
> > <name>Sue</name>
> > <company>Sue's Co.</company>
> > </customer>
> > </test>
> >
> > The output looks like this:
> >
> > DataSet name: test
> >
> > Table: product (1 rows)
> > Column: name
> > Row 0: Product 1
> >
> > Table: customer (2 rows)
> > Column: name
> > Row 0: Bill
> > Row 1: Sue
> > Column: company
> > Row 0: Bill's Co.
> > Row 1: Sue's Co.
> >
> > Questions:
> >
> > 1) I think I see why the test_Id column gets created "on the fly" for
> > the "customer" table in the first XML example. A "test" table got
> > created which might have multiple rows. So each row of the "customer"
> > table has to have some way of relating back to its parent table row,
> > which is what "test_Id" contains. But why does the "test" table
> > itself need a "test_Id" column?
> >
> > 2) In the first example a "test" table got created and the name of the
> > DataSet stayed at the default "NewDataSet". In the second example there
> > was no "test" table created. Instead the name of the DataSet is "test"
> > and there is a "product" table and "customer" table. Since there is no
> > "test" table there is no need for the "test_Id" column in any of the
> > tables that do exist. Why does it work this way? Why would just changing
> > that one element (ie. <product>) make such a big difference in the way the
> > way the DataSet is constructed.
> >
> > Any help appreciated. And again if you know of some good reference books
> > or links where these issues are discussed that would be fantastic.
> >
> > Thanks in advance.
> >