Entity bean mapping to multiple tables.

Question

Hello,
Is it possible to map several tables with only one BMP?
if so please send me an example (class bean)
Thanks in advance

Answer 1

hi,
yes, entity bean can be mapped to multiple tables provided it is bean managed entity bean.
since, container cannot prepare complex quries so that we need to rely on bean managed persistance.
Ex : Assume you have two table like X, Y
where X table having fields (int x primarykey, varchar str) and Y table having fields (varchar name primarykey, int y).
Now you should design a primary key class of your own as shown below:
public class BeanPriamkey implements java.io.Serializable
protected int x;
protected String name;
public BeanPramkey()
//initialzation part
public BeanPramkey(int x,String str)
//initialzation part
public String toString()
//return object value as string
public int hashCode()
//return an int value
public boolean equals(BeanPramkey)
public int getX()
return x;
public String getStr()
return str;
now your entity bean would be like this
public class Mybean implements EntityBean
int x,y;
String str,name;
BeanPriamkey primekey;
public BeanPrrmkey ejbCreate(int x,String name)
//fetch the rows from the tables X and Y ;
//if the rows exists int the tables create beanprimkey object with x and name and return refernce of the Beanprimkey class object
public BeanPrimkey findByPrimarykey(BeanPrimkey )
//first extract values of x and str from BeanPrimkey
and chek X and Y table for corresponding rows if exists return the reference of BeanPrimkey else return null
public void ejbStore()
BeanPrimkey prikey = (BeanPrimkey) entityContext.getPrimarykey();
int x = prikey.getX();
String st = prikey.getStr();
update X and Y tables using x and str;
public void ejbLoad()
BeanPrimkey prikey = (BeanPrimkey) entityContext.getPrimarykey();
int x = prikey.getX();
String st = prikey.getStr();
fetch the rows from X and Y tables using x and str;
and assing the row values to bean instance variables.
public void ejbPassivate()
//code for release the resources
public void ejbActivate()
//code for aquiring the resource
public void setEntityContext(EntityContext ec)
this.ec = ec;
protected EntityContext ec;