Details
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Improvement
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Status: Resolved
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Major
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Resolution: Fixed
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4.0
Description
Currently, it is not easily possible to reference columns in the main select from a subselect.
For example, to select authors which have published exactly one book, one can use the SQL:
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.