[Metamodel Wiki] Update of "examples/UpdatingData" by KasperSorensen

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The "examples/UpdatingData" page has been changed by KasperSorensen:
https://wiki.apache.org/metamodel/examples/UpdatingData

Comment:
Added "Updating data" example page

New page:
= Updating data =

Modifying data is done by means of implementing your own update scripts that are then submitted to the DataContext's executeUpdate(...) method. This approach guarantees isolation and coherence in all update operations. Here is a simple example:

{{{#!java
File myFile = new File("unexisting_file.csv");

UpdateableDataContext dataContext = DataContextFactory.createCsvDataContext(myFile);
final Schema schema = dataContext.getDefaultSchema();
dataContext.executeUpdate(new UpdateScript() {

    public void run(UpdateCallback callback) {
    
        // CREATING A TABLE
    
        Table table = callback.createTable(schema, "my_table")
            .withColumn("name").ofType(VARCHAR)
            .withColumn("gender").ofType(CHAR)
            .withColumn("age").ofType(INTEGER)
            .execute();
        
        // INSERTING SOME ROWS
        
        callback.insertInto(table).value("name","John Doe").value("gender",'M').value("age",42).execute();
        callback.insertInto(table).value("name","Jane Doe").value("gender",'F').value("age",42).execute();
    }
  
});
}}}

If you just want to insert or update a single record, you can skip the UpdateScript implementation and use the pre-built InsertInto, Update or DeleteFrom classes. But beware though that then you don't have any transaction boundaries or isolation inbetween those calls:

{{{#!java
Table table = schema.getTableByName("my_table");
dataContext.executeUpdate(new InsertInto(table).value("name", "Polly the Sheep").value("age", -1));
dataContext.executeUpdate(new Update(table).where("name").eq("Polly the Sheep").value("age", 10));
dataContext.executeUpdate(new DeleteFrom(table).where("name").eq("Polly the Sheep"));
}}}

... And just to go full circle, here's how you can continue to explore the data:

{{{#!java
System.out.println("Columns: " + Arrays.toString(table.getColumnNames()));

DataSet ds = dc.query().from(table).select(table.getColumns()).orderBy(table.getColumnByName("name")).execute();
while (ds.next()) {
    System.out.println("Row: " + Arrays.toString(ds.getRow().getValues()));
}
}}}
This snippet will print out:
{{{
Columns: [name, gender, age]
Row: [Jane Doe,F,42]
Row: [John Doe,M,42]
}}}