Hibernate version: 2.0

[b]My Sql Query is :

String SQL_QUERY ="from MaOwnXref as A where A.OWN_MA_USR_ID= 'MSTRADM'" ;

ArrayList lst = (ArrayList) hSession.createQuery(SQL_QUERY) .list();


The database is MS Sql.

Now when i view the contents of the list "lst" in debug mode i see many rows in the list but all the elements in the list are the same.

When i execute the same Sql query that appeared on the console in Query Analyzer -- i get many rows as resultset.

Can anyone help me?

you most likely have more than one row with the same id...not healthy ;)

Which id you are speaking of?

My database table has the following collumns
OWN_MA_USR_ID
MA_USR_ID

This table represents the parent-child relationship. where OWN_MA_USR_ID is the parent and MA_USR_ID is the child. So one parent can have many childs. so i am trying to retreive all the childrens of a particular parent.

btw. you do know that the query you show is a HQL query not SQL query ?

i dont know how you have mapped your object model so can't help you much.

i got what the problem is but i dont know how to solve it --


The problem is that the collumns of the table --OWN_MA_USR_ID and MA_USR_ID together form a composite key and both are strings --

and i changed the mapping file as

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

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 2.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-2.0.dtd">
<hibernate-mapping package="com.abcea.mas.tablemapping">
<class name="com.abcea.mas.tableobj.MaOwnXref" table="MA_OWN_XREF_T">
<composite-id unsaved-value="none">
<key-property name="OWN_MA_USR_ID" type="java.lang.String"/>
<key-property name="MA_USR_ID" type="java.lang.String"/>
</composite-id>
</class>
</hibernate-mapping>

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

now its asking me to implement equals() and hashcode() in the persistent class.
i have implemeted equals() but not able to implement hashcode() as both the table collumns are strings.

can anyone tell me how to implement hashcode here?

use the search abhilash!

http://hibernate.org/109.html

besides a long text about what is important about equals and hashcode it also has links to pages explaining the basics for writing equals and hashcodes

Why can't you implement HashCode on Strings ?

Thanks -- Max and Preston.

I have implemented equals and hashcode. But the equals method is slowing down my Query.

Can you give me some suggestions?

what do you do in your equals method since it hogs down your query ?

my equals method looks like this:


public boolean equals(Object other) {
if (this == other) return true;
if ( !(other instanceof MaOwnXref) ) return false;

final MaOwnXref cat = (MaOwnXref) other;

if ( !cat.getOWN_MA_USR_ID().equalsIgnoreCase( getOWN_MA_USR_ID() ) ) return false;
if ( !cat.getMA_USR_ID().equalsIgnoreCase( getMA_USR_ID() ) ) return false;

return true;
}

that isn't special and if that affects your query your query must be insanely big ?

why is ignore case relevant ?

and did you remember to implement a proper hashcode impl ?

i have IgnoreCase because OWN_MA_USR_ID and MA_USR_ID are strings.

It is mainly slow because my Query returns a large result set - some 1300 rows. but i works perfectly fine when i have a small resultset.

but if you hashcode has a good spread of values then this should not affect you at all with 1300 elements

Thanks max,
the problem was with hashcode() method -- i implemented it properly and now there are no problems.