Query query = new Query();
Select select = new Select();
select.addSymbol(new AllSymbol());
query.setSelect(select);
From from = new From();
Query query2 = new Query();
select = new Select();
select.addSymbol(new AllSymbol());
query2.setSelect(select);
From from2 = new From();
from2.addGroup(new GroupSymbol("t1")); //$NON-NLS-1$
from2.addGroup(new GroupSymbol("t2")); //$NON-NLS-1$
query2.setFrom(from2);
SubqueryFromClause sfc = new SubqueryFromClause("x", query2);//$NON-NLS-1$
sfc.setOptional(true);
from.addGroup(new GroupSymbol("t1")); //$NON-NLS-1$