I have 2 tables:
First one has id, column1, column2, column3.
Second one has id, column1, column2, column4.
Respective entity for the first one:
#Entity
public class FirstEntity {
#Id
private Integer id;
#OneToMany
#JoinColumns({
#JoinColumn(name = "column1", referencedColumnName = "column1"),
#JoinColumn(name = "column2", referencedColumnName = "column2")
})
private List<SecondEntity> secondEntity;
}
So join works fine with one exception: column2 may be null in both tables. And in that case rows with same column1 values where column2 is null should be joined as well.
With SQL I succeed in achieving this by updating join condition to
table1.column1 = table2.column1 and (coalesce(table1.column2, '') = coalesce(table2.column2, '')).
What can be done with Jpa (or Hibernate in particular) in order to get secondEntity field set for null column as well?
Related
For simplicity I'll chop the tables down quite a bit
Given the tables REPORT_DOWNLOAD, REPORT
REPORT has ID, NAME
REPORT_DOWNLOAD has ID, FK_REPORT_ID
I essentially want to build the query:
SELECT R.NAME, RD.ID FROM REPORT_DOWNLOAD RD, REPORT R WHERE
RD.FK_REPORT_ID = R.ID
My entity for REPORT_DOWNLOAD essentially looks like
#ManyToOne(fetch = FetchType.LAZY)
#JoinColumn(name = "FK_REPORT_ID", referencedColumnName = "ID", nullable = false)
private ReportOrm report;
But that queries the whole REPORT table. Is there a way to reference just the NAME column from the entity?
#SomeAnnotationThatMagicallyPulls("FK_REPORT_ID", "NAME")
private String reportName;
I feel like there must be some Hibernate / JPA magic here that I could use
If I setup a parent/child relationship with both parent and child having additionalcriteria constraints, and then use #JoinFetch then childs additionalcriteria are ignored.
For example:
TableA.java:
#javax.persistence.Entity
#Table(name = "TABLE_A")
#AdditionalCriteria("this.tableAfield2=:propA")
public class TableA {
#Id
#Column(name = "TABLEAFIELD1")
private String tableAfield1;
#Column(name = "TABLEAFIELD2")
private String tableAfield2;
#JoinColumn(name = "TABLEAFIELD2", referencedColumnName = "TABLEBFIELD1", insertable = false, updatable = false)
#OneToOne(fetch = FetchType.EAGER)
// #JoinFetch(JoinFetchType.OUTER)
private TableB tableAtableB;
}
TableB.java:
#javax.persistence.Entity
#Table(name = "TABLE_B")
#AdditionalCriteria("this.tableBfield2=:propB")
public class TableB {
#Id
#Column(name = "TABLEBFIELD1")
private String tableBfield1;
#Column(name = "TABLEBFIELD2")
private String tableBfield2;
public String getTableBfield1() {
return tableBfield1;
}
public String getTableBfield2() {
return tableBfield2;
}
}
Main:
em.setProperty("propA", "propertyAValue");
em.setProperty("propB", "propertyBValue");
CriteriaBuilder cb = em.getCriteriaBuilder();
CriteriaQuery<TableA> criteriaQuery = cb.createQuery(TableA.class);
Root<TableA> tableA = criteriaQuery.from(TableA.class);
Predicate pred = cb.equal(tableA.get("tableAfield1"), "keyA1");
criteriaQuery.where(pred);
List<TableA> results = em.createQuery(criteriaQuery).getResultList();
With tableA set as per the example (with JoinFetch commented out)
the applications creates 2 SQLs
SELECT TABLEAFIELD1, TABLEAFIELD2 FROM TABLE_A WHERE ((TABLEAFIELD1 = ?) AND (TABLEAFIELD2 = ?))
bind => [keyA1, propertyAValue]
SELECT TABLEBFIELD1, TABLEBFIELD2 FROM TABLE_B WHERE ((TABLEBFIELD1 = ?) AND (TABLEBFIELD2 = ?))
bind => [propertyAValue, propertyBValue]
which is fine, as eclipselink is loading the table_b on demand.
but for our application we need to have a single SQL, as there maybe 1000s of rows and we need a single join.
So, if I put back the #JoinFetch then the sql generated is;
SELECT t1.TABLEAFIELD1, t1.TABLEAFIELD2, t0.TABLEBFIELD1, t0.TABLEBFIELD2 FROM TABLE_A t1 LEFT OUTER JOIN TABLE_B t0 ON (t0.TABLEBFIELD1 = t1.TABLEAFIELD2) WHERE ((t1.TABLEAFIELD1 = ?) AND (t1.TABLEAFIELD2 = ?))
bind => [keyA1, propertyAValue]
the additionalCriteria from TableB is not added (there is no t0.tableBField1=? (propertyBValue) )
Any suggestions? Its driving me mad.
Many thanks
For completeness here are the tables
create table TABLE_A (
TABLEAFIELD1 varchar2(20),
TABLEAFIELD2 varchar2(30),
CONSTRAINT tableApk PRIMARY KEY (TABLEAFIELD1)
) ;
create table TABLE_B (
TABLEBFIELD1 varchar2(20),
TABLEBFIELD2 varchar2(30),
CONSTRAINT tableBpk PRIMARY KEY (TABLEBFIELD1)
) ;
insert into TABLE_A (TABLEAFIELD1,TABLEAFIELD2) values ('keyA1','propertyAValue');
insert into TABLE_A (TABLEAFIELD1,TABLEAFIELD2) values ('keyA2','propertyAValue');
insert into TABLE_A (TABLEAFIELD1,TABLEAFIELD2) values ('keyA3','random');
insert into TABLE_B (TABLEBFIELD1,TABLEBFIELD2) values ('propertyAValue','propertyBValue');
So this is a long term bug with eclipselink and doesn't look like it will be fixed.
The solution was to change
#JoinFetch(JoinFetchType.OUTER)
to
#BatchFetch(BatchFetchType.JOIN)
This doesn't exactly have the result I was hoping for, originally wanted the generated sql to include an OUTER JOIN,
but BatchFetch results in only 2 SQLs, one to get the Table_A items, then another to fetch all the Table_B items (including the additionalcriteria requirements)
I thought I understood hibernate's fetching strategies, but it seems I was wrong.
So, I have an namedNativeQuery:
#NamedNativeQueries({
#NamedNativeQuery(
name = "getTest",
resultClass = ArticleOnDate.class,
query = "SELECT `a`.`id` AS `article_id`, `a`.`name` AS `name`, `b`.`price` AS `price` FROM article a LEFT JOIN price b ON (a.id = b.article_id) WHERE a.date <= :date"
)
})
#Entity()
#Immutable
public class ArtikelOnDate implements Serializable {
#Id
#OneToOne
#JoinColumn(name = "article_id")
private Article article;
...
}
Then I call it:
Query query = session.getNamedQuery("getTest").setDate("date", date);
List<ArticleOnDate> list = (List<ArticleOnDate>) query.list();
The query returns thousand of entities... Well, ok, but after that query hibernate queries thousand other queries:
Hibernate:
select
article0_.id as id1_0_0_,
article0_.bereich as name2_0_0_,
price1_.price as price1_14_1_
from
article artikel0_
where
artikel0_.id=?
Ok, that's logic, because the #OneToOne relation is fetched eagerly. I don't want to fetch it lazy, so I want a batch fetching strategy.
I tried to annotate the Article property but it didn't work:
#Id
#OneToOne
#JoinColumn(name = "article_id")
#BatchSize(size=100)
private Article article;
So what can I do to fetch the relation in a batch?
I have done a code change in a domain class(JPA). I added an ElementCollection to an entity:
#ElementCollection(targetClass = String.class)
#CollectionTable(name = "T_NETWORK_STATE", joinColumns = {#JoinColumn(name = "NETWORK_ID")})
#Column(name = "STATE")
private Set<String> states = new HashSet<>();
Now I want to write a flyway update db script for this change. I need the SQL DDL for the table T_NETWORK_STATE.
I am new to writing sql queries. any help will be appreciated!
CREATE TABLE T_NETWORK_STATE (
NETWORK_ID INT,
STATE VARCHAR(100),
UNIQUE INDEX (NETWORK_ID, STATE),
FOREIGN KEY (NETWORK_ID) REFERENCES NETWORK(NETWORK_ID)
);
I want to make a JPQL query with a collection of non entities. This is my Table entity :
#Entity
#Table(name = "ct_table")
public class Table {
...
#CollectionOfElements(fetch = FetchType.EAGER)
#JoinTable(name = "ct_table_result", joinColumns = #JoinColumn(name = "tableId"))
#MapKey(columns = { #Column(name = "label") })
#Column(name = "value")
private Map<String, String> tableResults;
...
then I try to make a query like this
select count(*) from table where table.tableResults['somekey'].value='somevalue'
but I get the following exception:
Cannot create element join for a collection of non-entities!
Any suggestion??
thanks for your time
EDIT:
I use JPA 1 and hibernate 3.3. Default libraries in JBoss 5
The JPA 2 spec (page 139) defines the KEY() and VALUE() functions to access the key and the value of a map-valued element collection:
select count(t.id) from Table t
where KEY(t.tableResults) = 'somekey' and VALUE(t.tableResults) = 'somevalue'