[FIXED] Hibernate (or EntityManager?) adding "where 0=1" to query

Issue

I'm using the JPA EntityManager + Hiberate, and a myserious piece of the where clause is appearing. The debug from Hibernate is basically showing:

select /* bunch of columns */
from some_table
where /* several filters */
  and 0=1

This is happening when running javax.persistence.Query.getResultList. The Query has an array of Predicates in its where clause, but rest assured that 0 = 1 is not one of them.

I can find no possible reason why the 0=1 part is included in the query. Any ideas? I'd search for an answer first, but search engines ignore =.

Solution

This is how a disjunction is translated to SQL. See the javadoc for disjunction()

Create a disjunction (with zero disjuncts). A disjunction with zero disjuncts is false.

So, when an empty disjunction is created, it only contains the clause 1 = 0 (false). When additional predicates are added to the disjunction, they're simply added to the initial (false) one, separated with an or:

where 1 = 0 or ...

If you use a conjunction, it will be translated to

where 1 = 1 and ...

Answered By - JB Nizet
Answer Checked By - Marie Seifert (JavaFixing Admin)