Hi there,
Not sure what you mean with "politic", but certainly asking questions like
this is ALWAYS fine :-)
Actually you can select from a subquery, you just have to wrap the subquery
in a new FromItem(subQuery). Then select from that FromItem.
Regarding typed columns, I am happy to see some initiatives there. Main
advantage from my standpoint is that then we could have also typed return
values when getting stuff out of datasets. Example/suggestion code:
DataSet ds = ...
> TypedColumn<String> c = ...
> String s = ds.getValue(c);
Normally I would need to do a cast (to the 's' variable) there ...
The other thing you mention is having a Person type or so. I would not
agree that table could ever be a specialization of column. But that is in
my opinion then more about having a typed/mapped DataSet.
Example/suggestion code:
DataSet ds = ...
> MappedDataSet<Person> mds = new MappedDataSetImpl<Person>(ds,
> personMapper);
> while (mds.next()) {
> Person person = mds.getObject();
> doSomething(person);
> }
That would be pretty cool for many purposes I guess!
2015-05-31 15:00 GMT+02:00 TearsRed <[email protected]>:
> I don't know if it's politic to send you email, but there is no Issue
> panel in MetaModel's page on Github.
> I've searched http://wiki.apache.org/metamodel/ with keyword "subquery",
> but there is no result.译
> I used to think if org.apache.metamodel.query.Query implements
> org.apache.metamodel.schema.Table so I can do it like
> dataContext.query().from(query), but it doesn't.
> So I ask you how to do SubQuery in MetaModel.
>
> In fact, I think the api of MetaModel can do a big change, like this:
> TableLike = dataContext.query().from(TableLike... tables)
> TableLike = dataContext.query().from(TableLike...
> tables).select(ColumnLike... columns)
> Filter = ColumnLike.operator(value)dataContext.query().from(TableLike...
> tables).select(ColumnLike... columns).where(Filter...
> filters).groupBy(ColumnLike... columns)
> There are 3 main interfaces: TableLike , ColumnLike , Filter.
> query, table, view are all TableLike;column in a query, column in a table
> are all ColumnLike;filter is generated by ColumnLike...
> By the way, if the Column Type can be represent by the class of Column,
> things may be better.Maybe we can't make Column a generic class like
> Column<Integer>, because we can't use it like Column<Person>(wait, wait,
> wait, maybe we can if Person is just a java bean.... WOW, it seems that
> TableLike is in fact a subclass of ColumnLike).... So we can have some
> simple column class like IntegerColumn, StringColumn, DateColumn.....
> AgainI don't know if it's politic to send you email. If it's not, ignore
> the email. If it doesn't matter, will you reply me?
>
