[hibernate-issues] [Hibernate-JIRA] Commented: (HHH-2776) Restrictons.in(..) generates invalid SQL if list of values is empty

[Steve Ebersole (JIRA)]

    [ http://opensource.atlassian.com/projects/hibernate/browse/HHH-2776?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=32252#action_32252 ] 

Steve Ebersole commented on HHH-2776:
-------------------------------------

Well neither #1 nor #2 were solutions, they were merely points...

A user reporting that something they are trying that is not documented to work does not work is never ever ever going to be accepted as a bug.  

So you are ok with "creating an API-instead-of-SQL-generating-platform" that happens to only work on MySQL because it uses some MySQL extension beyond what standard SQL allows?  LOL, comon.

I never said this should not be implemented (perhaps this is why I marked that we should implement this in HQL over a year ago???), but clearly implementing this based on a non-standard SQL syntax that happens to work on your selected database is a bit non-community-friendly wouldnt you say?

Sure feel free to implement it.  You just need to finish up the research I started and find out which SQL spec added support for NULLs as explicit in-value-list items and then how many common databases support that spec.  

> Restrictons.in(..) generates invalid SQL if list of values is empty
> -------------------------------------------------------------------
>
>                 Key: HHH-2776
>                 URL: http://opensource.atlassian.com/projects/hibernate/browse/HHH-2776
>             Project: Hibernate Core
>          Issue Type: New Feature
>          Components: query-criteria, query-hql
>    Affects Versions: 3.2.2
>         Environment: Hibernate 3.2.2.ga, MySQL 4.1.18, Windows XP
>            Reporter: Adrian Smith
>            Assignee: Steve Ebersole
>
> I have classes called A and B. There is a 1:n relationship from A to B.
> Class B has the following in its mapping file:
>    <many-to-one name="a" class="A" column="fk_a_id" not-null="true" />
> If I write the following code:
>     List<B> foo() {
>        List<A> aList = ....
>        Session session = ....
>        Criteria query = session.createCriteria(B.class);
>        query.add(Restrictions.in("a", aList));
>        return query.list();
>    }
> Then all works fine and the results I want are returned. However, if aList is empty (i.e. aList.size()==0) then the query.list function generates and executes invalid SQL for MySQL.
> java.sql.SQLException: Syntax error or access violation message from server: "You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near ')' at line 1"
> I imagine that it is generating SQL like IN () which isn't valid.
> I realize it's a bit ridiculous to want to find the rows where a field is IN the empty list. Nothing will ever be returned. However, in my opinion it should still be allowed, and return no rows, just as saying "WHERE 1=2" is allowed, just doesn't return any rows.

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