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keeping a single row in a table

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streetfi8er

Post subject: keeping a single row in a table

Posted: Sun Oct 02, 2011 8:42 am

Newbie

Joined: Sun Oct 02, 2011 8:23 am
Posts: 2

hi, i have two tables.. Employee and salary. I intend that each customer must have only one entry in the salary table.
the table structure is :
customer:
EMPID primary key,
EMPNAME

salary :
SALID primary key,
netSal
cust_id(foreign key references customer(cust_id))

Now the problem is , one customer can have mulitple rows in the salary table. I tried using one-to-one mapping in the salary.hbm file but that doesn't help. Also i think if i use in the salary table the primary key as the foreign key of customer table then the problem might be solved. but i don't know how to write the corresponding mapping files.
Here are the two hbm files:

salary.hbm.xml:

Code:

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE hibernate-mapping PUBLIC
        "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
        "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<hibernate-mapping>

<class name="employee.Salary" table="salary">
<id 
name = "salId"
column = "SALID">
<generator class="increment"></generator>
</id>

<property 
name = "netSal"
column = "netsal">
</property>

<!--  <many-to-one class="Employee" name="employee"
 unique = "true" >
 <column name = "EMPID"/>
 
 </many-to-one> -->

 <one-to-one  name="employee" class = "Employee" 
 >
 </one-to-one> 

</class>
</hibernate-mapping>

Employee.hbm.xml file:

Code:

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE hibernate-mapping PUBLIC
        "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
        "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<hibernate-mapping>
<class name = "Employee" table = "employee">
<id 
name = "EmpId"
type = "int"
column = "EMPID">
<generator class = "assigned"></generator>
</id>

<property
name="EmpName"
column = "EMPNAME">
</property>

</class>

</hibernate-mapping>

The corresponding pojo files are:

salary.java:

Code:

public class Salary{
   Double netSal=0.0;
   int salId;
   Employee employee;
     .... //getters and setters

Employee.java

Code:

public class Employee{
int Empid;
String Empname;
//getters and setters

Also this is a web app and i have an index page where i am creating a SessionFactory but as the page can be referenced many times in a session, so each time a new SessionFactory is created. So where should the SessionFactory be initialised?
Thanks.

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msknapp

Post subject: Re: keeping a single row in a table

Posted: Sun Oct 02, 2011 2:51 pm

Newbie

Joined: Sun Sep 25, 2011 4:05 pm
Posts: 12

Quote:

I tried using one-to-one mapping in the salary.hbm file but that doesn't help

You have a unidirectional one-to-one association, no join table, see 8.2.2 in the manual:
http://docs.jboss.org/hibernate/core/3. ... tional-121

You should use the second of the two examples in that section. The one problem I noticed between yours and the example is the id generator is "assigned" in yours but should use "foreign" for the salary entity.

Quote:

See 1.1.6 in the manual:
http://docs.jboss.org/hibernate/core/3. ... pp-helpers

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streetfi8er

Post subject: Re: keeping a single row in a table

Posted: Mon Oct 03, 2011 7:27 am

Newbie

Joined: Sun Oct 02, 2011 8:23 am
Posts: 2

thanks a lot for the reply..
i tried modifying the salary.hbm file and also the table as:
salary.hbm:

Code:

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE hibernate-mapping PUBLIC
        "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
        "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<hibernate-mapping>

<class name="Salary" table="salary">

 <id name="salId" column="SALID">
        <generator class="foreign">
            <param name="property">employee</param>
        </generator>
</id> 

<property 
name = "netSal"
column = "netsal">
</property>

 <one-to-one  name="employee" class = "Employee"  constrained = "true"
 >
 </one-to-one>


</class>
</hibernate-mapping>

the salary table is as:

Code:

create table salary(salid int(5) primary key,netsal double)

Now the problem is in deleting. If i delete an employee then i get foreign key constraint even if add cascade = "all" in employee as follows:

employee.hbm:

Code:

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE hibernate-mapping PUBLIC
        "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
        "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<hibernate-mapping>
<class name = "Employee" table = "employee">
<id 
name = "EmpId"
type = "int"
column = "EMPID">
<generator class = "assigned"></generator>
</id>

<property
name="EmpName"
column = "EMPNAME">
</property>

 <one-to-one
name="salary"
class="Salary"
cascade = "all">
</one-to-one> 



</class>

</hibernate-mapping>

where the corresponding pojo is:
employee.java

Code:

public class Employee
{
int EmpId;
String EmpName;
Salary salary;
//getters and setters
}

So, do i have to delete the salary row before deleting the corresponding Employee or is there any other way?
Thanks.

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