Can I get the SQL string from a JPA Query object?

JPA Specification

While there is not standard JPA functionality to achieve this goal, you can still extract the SQL query from a JPQL or Criteria API Query using the JPA provider-specific API.

Hibernate Types

Starting with the 2.9.11 version, the Hibernate Types open-source project offers the SQLExtractor utility that allows you to get the SQL query from any JPQL or Criteria API query, no matter you are using Hibernate 5.4, 5.3, 5.2, 5.1, 5.0, 4.3, 4.2, or 4.1.

Get the SQL statement from a JPQL Query

Let's assume we have the following JPQL query:

Query jpql = entityManager.createQuery("""
    select 
       YEAR(p.createdOn) as year, 
       count(p) as postCount 
    from 
       Post p 
    group by 
       YEAR(p.createdOn)
    """, Tuple.class
);

With Hibernate Types, extracting the Hibernate-generated SQL query is as simple as that:

String sql = SQLExtractor.from(jpql);

And, if we log the extracted SQL query:

LOGGER.info("""
    The JPQL query: [
        {}
    ]
    generates the following SQL query: [ 
        {}
    ]
    """,
    jpql.unwrap(org.hibernate.query.Query.class).getQueryString(),
    sql
);

We get the following output:

- The JPQL query: [
    select    
        YEAR(p.createdOn) as year,    
        count(p) as postCount 
    from    
        Post p 
    group by    
        YEAR(p.createdOn)
]
generates the following SQL query: [
    SELECT 
        extract(YEAR FROM sqlextract0_.created_on) AS col_0_0_,
        count(sqlextract0_.id) AS col_1_0_
    FROM 
        post p
    GROUP BY 
        extract(YEAR FROM p.created_on)
]

Notice that we unwrapped the JPA Query to the Hibernate org.hibernate.query.Query interface which provided the getQueryString method we can use to log the associated JPQL query string.

Get the SQL statement from a JPA Criteria API Query

The SQLExtractor is not limited to JPQL queries. You can use it with Criteria API queries as well, as illustrated by the following example:

CriteriaBuilder builder = entityManager.getCriteriaBuilder();

CriteriaQuery<PostComment> criteria = builder.createQuery(PostComment.class);

Root<PostComment> postComment = criteria.from(PostComment.class);
Join<PostComment, Post> post = postComment.join("post");

criteria.where(
    builder.like(post.get("title"), "%Java%")
);

criteria.orderBy(
    builder.asc(postComment.get("id"))
);

Query criteriaQuery = entityManager.createQuery(criteria);

String sql = SQLExtractor.from(criteriaQuery);

assertNotNull(sql);

LOGGER.info("""
    The Criteria API, compiled to this JPQL query: [
        {}
    ]
    generates the following SQL query: [
        {}
    ]
    """,
    jpql.unwrap(org.hibernate.query.Query.class).getQueryString(),
    sql
);

When running the above test case, we get the following SQL query:

- The Criteria API, compiled to this JPQL query: [
    select 
        pc 
    from 
        PostComment as pc 
    inner join 
        pc.post as p 
    where 
        p.title like :param0 
    order by 
        pc.id asc
]
generates the following SQL query: [
    SELECT 
        pc.id AS id1_1_,
        pc.post_id AS post_id3_1_,
        pc.review AS review2_1_
    FROM 
        post_comment pc
    INNER JOIN 
        post p ON pc.post_id=p.id
    WHERE 
        p.title LIKE ?
    ORDER BY 
        pc.id ASC
]

The Criteria API is first compiled to a JPQL query, as illustrated by the getQueryString() method call.

The intermediary JPQL query is further translated to an SQL query, which is properly resolved by the SQLExtractor utility.

If you only want to know how your JPQL or Criteria Query gets translated to the SQL dialect of your database you can enable fine grained logging in the persistence xml and then look into your log files.

The property name and value depends on your JPA implementation. Here is an example of the relevant part of persistence.xml for EclipseLink:

<properties>
    <property name="eclipselink.logging.level" value="FINEST"/>
</properties>

For Eclipselink: you can extract the SQL the following way:

query.unwrap(EJBQueryImpl.class).getDatabaseQuery().getSQLString()

It works only after the query has been executed.