How to get multiple rows based on a single column value?

[Kunal Lakhani]

Hello
I need to retrieve rows from database based on a particular column value.

//eno contains the value passed to the method, in this case its 1110.
Criteria cr = session.createCriteria(org.nit.Entity.TuitionPaymentEntity.class)
		.add(Restrictions.eq("enrollmentNo", eno));
		
		List<TuitionPaymentEntity> l = cr.list();
		
		for(TuitionPaymentEntity tpe : l){
			System.out.println(tpe.getDue()); //prints the due column value
		}

In this example, there are 4 rows with enrollmentNo as 1110. It runs successfully, but prints the same row data 4 times. (In the table enrollmentNo is the foreign key, does it affects the output? i guess no)

[Kunal Lakhani]

What changes does my code need?

[Kunal Lakhani]

I have tried with Native Sql, but the result is same.

Code

String sql = "Select * from tuitionpayment where enrollmentno=?";
		Query cr = session.createSQLQuery(sql).addEntity(org.nit.Entity.TuitionPaymentEntity.class).setLong(0, eno);
		
		List<TuitionPaymentEntity> l = cr.list();
		System.out.println(l.size());
		System.out.println(l);
		
		for(TuitionPaymentEntity tpe : l){
			System.out.println(tpe.getDue());
		}

Output

4
[org.nit.Entity.TuitionPaymentEntity@4d8d50, org.nit.Entity.TuitionPaymentEntity@4d8d50, org.nit.Entity.TuitionPaymentEntity@4d8d50, org.nit.Entity.TuitionPaymentEntity@4d8d50]
4000
4000
4000
4000

The query gets the same rows 4 times, and it returns the same object (Verified after printing the list)

What changes does my code needs?

[Bill Gorder]

Why you are getting duplicates is impossible to diagnose without knowing your relationships.

You could add

cr.setResultTransformer(Criteria.DISTINCT_ROOT_ENTITY);

after you are done setting your restrictions. Be aware you will still contain all the duplicates in your result set, this does not reduce the amount of data fetched from the DB or what is sent over the wire. The removing of duplicates is handled on the java side.

Alternatively you can use projections. If you go that route be aware you have to specify all the property's you want fetched.

[Kunal Lakhani]

The table contains a foreign key , i.e enrollmentno. However, the query gets to know that there are 4 rows with the enrollment no given (and i need all those 4 rows), but it loads the same row(only a single row) four times

[Kunal Lakhani]

You could add

view plaincopy to clipboardprint?
cr.setResultTransformer(Criteria.DISTINCT_ROOT_ENTITY);


after you are done setting your restrictions.

This gets me a single record with the given enrollment number. But i need all those 4 rows with the given enrollment Number

[Bill Gorder]

The problem is the 4 rows you are getting back are the same entity (they are duplicates). They have the same persistent id whatever that is for your TuitionPaymentEntity. If that were not the case then you would have more than one result. You need to re-examine your relationships and mappings.

[Kunal Lakhani]

My table Db Structure

enrollmentno number(5) not null
constraint tuitionpayment_fk 
References studentpersonal(ENROLLMENTNO)

The enrollment number used here (and in my code) refers to a primary key of another table(i.e ENROLLMENTNO column of studentpersonal table)

Here is the hbm.xml part for this structure

<class name="org.nit.Entity.TuitionPaymentEntity" table="TuitionPayment" >
<id name="enrollmentNo" type="java.lang.Long" column="enrollmentNo" >
<generator class="assigned"></generator>
</id>
....

Is this the problem? Is Foreign key mapped in a different way?

I have not coded for any type of mappings like one-to one or one-to-many.

[anuj pachauri]

i think are creating single session object..so
Try to create new session object and  then apply criteria query................
You will get different result .