ATG QueryBuilder: How to create nested queries / subqueries

I had to deal a good amount of time finding a way to query repositoy items that would match some relationships among different item descriptors. I was trying to look for a way to perform a join over different item descriptors, but at the end was able to solved it in a nested queries fashion. You know,

the typical thing in SQL where you filter by matching a column from the result of another query:

?

1 2 3 4 5 6

SELECT column_name [, column_name ] FROM   table1 [, table2 ] WHERE  column_name OPERATOR       (SELECT column_name [, column_name ]       FROM table1 [, table2 ]       [WHERE])

This in ATG can be done using a query builder operation called: createIncludesItemQuery. You can pass as parameter another query and the colum matching expression.

?

1 2 3 4 5 6 7 8 9 10 11 12

// Get guide items where tabs in the guide matches some other tabs query RepositoryItemDescriptor guideRepositoryItemDescriptor =                         getProductRepository().getItemDescriptor("guide"); RepositoryView guidesRepositoryView = guideRepositoryItemDescriptor.getRepositoryView();                 QueryBuilder guidesQueryBuilder = guidesRepositoryView.getQueryBuilder(); QueryExpression tabsPropertyExpression =             guidesQueryBuilder.createPropertyQueryExpression("tabs");                    // productTabsQuery is another query built Query productGuidesQuery =       guidesQueryBuilder.createIncludesItemQuery(tabsPropertyExpression, productTabsQuery); RepositoryItem[] guides = guidesRepositoryView.executeQuery(productGuidesQuery);