I am trying to execute this query using hibernate "select test_seq.nextval from dual" but am not sure how to do it. I need to get a new sequenceId for a class before I can insert it into the database. I cannot generate using <generator class="hilo"></generator> because the id is for a child and am trying to save it by putting it in a set of its parent.

P p = new P

C c1 = new C
c1.setPId = p.getId
c1.setSequenceId = need to get this "select test_seq.nextval from dual"

C c2 = new C
c2.setPId = p.getId
c2.setSequenceId = need to get this "select test_seq.nextval from dual"

p.addChild( c1 )
p.addChild( c2 )

Session.save( p ) - this will save the parent and children.

I need sequenceId when adding it to the parent, to differ the children from each other.

thanks

Hey, I guess it is a fairly bad idea to set the sequence number yourself in the db-layer.

Why don't you just save your Child before adding it to the parent collection?


simon

There is a foreign key between the parent and child, so the parent must be saved before the child for this link to work correctly

nope. Hibernate can accomodate this situation. The child class just needs to have an association pointing back to the parent and the columns it needs from the parent. Even if the values are generated in the database when the parent is saved.


For an example, this could be used in the composite-key of a child

In my first post I do save the parent first and the id is available via the specified getter method.

Here are my xml mappings Company is the parent and product and employee are children. I have a set for each child in the company.java class. After I got the sequenceId from the database, I thought I could just make one save method call to save everything to the database.


<class name="Company" table="Company">
<id name="companyId" column="companyId" type="long"
unsaved-value="null">
<generator class="hilo"></generator>
</id>
<property name="name" column="companyName" type="string"
length="15" not-null="true"/>
<property name="address" column="address" type="string"
length="25" not-null="true"/>

<set name="products" cascade="all" inverse="true">
<key column="companyId"/>
<one-to-many class="Product"/>
</set>
<set name="employees" cascade="all" inverse="true">
<key column="companyId"/>
<one-to-many class="Employee"/>
</set>
</class>

------------
<class name="Product" table="Product">
<composite-id name="ProductPK" class="ProductPK">
<key-property name="productId" type="long" column="productId"/>
</composite-id>
<property name="productName" column="productName" type="string" length="15" not-null="false"/>
<property name="productPrice" column="productPrice" type="double" not-null="false"/>
<property name="productDescription" column="productDescription" type="string"
length="50" not-null="false"/>
<many-to-one name="company" class="Company" column="companyId" not-null="true"/>
</class>


---------------

<class name="Employee" table="Employee">
<composite-id name="EmployeePK" class="EmployeePK">
<key-property name="ssn" type="integer" column="ssn"/>
<key-property name="firstName" column="firstName" type="string" length="15"/>
</composite-id>

<property name="lastName" column="lastName" type="string"
length="15" not-null="true"/>
<property name="salary" column="salary" type="double" not-null="true"/>

<many-to-one name="company" class="Company" column="companyId" not-null="true"/>

</class>

those mappings look fine.

Just create the product and employee, make sure to set the company for each of them like product.setCompany(parentCompany), add them to the set, then save the parent

I changed my product mapping to this, to get a generated ID from the db. When I did this, hibernate will try and update instead of inserting the data into the database. Not sure why on this.

<class name="Product" table="Product">
<id name="productId" column="productId" type="long"
unsaved-value="null">
<generator class="hilo"></generator>
</id>
<property name="productName" column="productName" type="string" length="15" not-null="false"/>
<property name="productPrice" column="productPrice" type="double" not-null="false"/>
<property name="productDescription" column="productDescription" type="string"
length="50" not-null="false"/>
<many-to-one name="company" class="Company" column="companyId" not-null="true"/>
</class>





Hibernate: select employee_.ssn, employee_.firstName, employee_.lastName as lastName1_, employee_.salary as salary1_, employee_.companyId as companyId1_ from Employee employee_ where employee_.ssn=? and employee_.firstName=?
Hibernate: select employee_.ssn, employee_.firstName, employee_.lastName as lastName1_, employee_.salary as salary1_, employee_.companyId as companyId1_ from Employee employee_ where employee_.ssn=? and employee_.firstName=?
Hibernate: insert into Company (companyName, address, companyId) values (?, ?, ?)
Hibernate: insert into Employee (lastName, salary, companyId, ssn, firstName) values (?, ?, ?, ?, ?)
Hibernate: insert into Employee (lastName, salary, companyId, ssn, firstName) values (?, ?, ?, ?, ?)
Hibernate: insert into Company (companyName, address, companyId) values (?, ?, ?)
Hibernate: insert into Company (companyName, address, companyId) values (?, ?, ?)
Hibernate: update Product set productName=?, productPrice=?, productDescription=?, companyId=? where productId=?

this is different from what you had above, did you mean this?

edit: by different I mean that product now has a generated id

Yes,

I changed it to see if I could get an auto generated id. I want the db to create the id for the product if possible.

I'm not familiar with the hilo generator, but do you need to specify a name for the generator?

In your original post, you showed code like:
P p = new P

C c1 = new C
c1.setPId = p.getId
p.addChild(c1);

but the "setPId" line should be
c1.setParent(p);

...unless addchild() does that.
There shouldn't even be a "setPId" method.

Maybe try using the native generator and map your classes following the suggestions in the Inheritance portion of the documentation. This lets hibernate worry about the relationships and the ids.