Hibernate HQL Count and Implicit Join result are different

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I have Class A with fields

Long id
B activity

And related class B

Long id
String name

Then I have the HQL query:

select a.id, a.activity.name from A a;

Some B fields on class A have null values, so left join gives more results than inner join.

I'm generating automatically the HQL, so I want the select and then the count:

select count(*) from A;

This gives me different results.

Is some way to resolve this, other than adding the explicit left join on the SQL (I'm receiving the HQL, can't change it).

join hibernate java
1 Answers

Try execute the count with the same query, this way:

Query query = getEm().createQuery("select a.id, a.activity.name from A a");

int count = query.getResultList().size();

Or if you want to create a native query, configure your persistence.xml to enable log statement. So you can modify the original select to make the count. Statement logging and statistics

  • hibernate.show_sql
  • hibernate.format_sql

  • hibernate.use_sql_comments

    <properties>
    <property name="hibernate.dialect" value="org.hibernate.dialect.MySQLDialect" />
    <property name="show_sql" value="true" />
    <property name="format_sql" value="true" />
    <property name="hibernate.hbm2ddl.auto" value="update" />
</properties>
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