[jira] [Created] (TORQUE-290) Improve building from clause in subselect

["Thomas Fox (JIRA)" <ji...@apache.org>]

Thomas Fox created TORQUE-290:
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             Summary: Improve building from clause in subselect
                 Key: TORQUE-290
                 URL: https://issues.apache.org/jira/browse/TORQUE-290
             Project: Torque
          Issue Type: Improvement
          Components: Runtime
    Affects Versions: 4.0
            Reporter: Thomas Fox
            Assignee: Thomas Fox


Currently, it is not easily possible to reference columns in the main select from a subselect.
For example:

Select authors which have published more than three books
SELECT * FROM author WHERE (SELECT COUNT(*) FROM book WHERE book.author_id=author.author_id)=1

One would like to achieve this by
Criteria subselect = new Criteria();
subselect.where(BookPeer.AUTHOR_ID, AuthorPeer.AUTHOR_ID);
subselect.addSelectColumn(new Count("*"));

Criteria criteria = new Criteria();
criteria.where(subselect, 1);

List<Author> result = AuthorPeer.doSelect(criteria);

but the SQL results in (note the additional author in the from clause of the subselect)
SELECT * FROM author WHERE (SELECT COUNT(*) FROM book, author WHERE book.author_id=author.author_id)=1

So the desired behavior is:
If a table also exists in the from clause of the outer criteria, it should not be added to the from clause of the subselect

NOTE1: This change can change the behaviour of Torque in existing code
NOTE2: Workarounds exist, e.g. defining the FROM clause of the subselect manually using Criteria.addFrom() or using "new ColumnImpl(null,null,null,AuthorPeer.AUTHOR_ID.getSqlExpression())" as join column in the WHERE clause of the subselect.Currently, it is not easily possible to reference columns in the main select from a subselect.
For examle

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