problem:
iam using postgresql database.

i have two tables one is class_definition with having column named class_id_pk which is primary key, and there is another table state_classes with column class_id_fk having the foreign key reference of class_id_pk. when i load session factory, it creates the extra empty column with name class_id_pk in state_classes table.in postgresql database.. i dont want this to happen adding unnecessary extra column...

is there any attribute to avoid creation of extra column?

ex: table1 : class_definition
columns: class_id_pk, class_name;
class_id_pk primary key btree (class_id_pk)


table2: state_classes
columns: state_classes_id_pk, class_id_fk

class_id_fk FOREIGN KEY (class_id_fk) REFERENCES class_definition(class_id_pk) MATCH FULL ON UPDATE NO ACTION ON DELETE CASCADE,

after running session factory, with in hibernate.cfg.xml having attribute hbmddl_auto update propery,,


it creates extra columns in state_classes, after generating hibernate generating mappings we get in postgres data base with

table2: state_classes
columns: state_classes_id_pk, class_id_fk. class_id_pk
,

What is your hibernate.cfg.xml file? Hibernate doesn't do any update to the schema unless you put hbm2ddl option in your config.

i added <property name="hibernate.hbm2ddl.auto"

but, is not another way, to avoid an extra column not to add to database, with out disturbing auto update as false. (only particular column should not be updated, is any attribute to declare in hbm.xml file)

I I get you correctly, no. You can't ask to update the schema, but not the columns...

In your case, if Hibernate adds a column when accessing the schema, I think that's because your mapping is not correct.

See the different values of hbm2ddl.auto (the reference documentation): http://www.hibernate.org/hib_docs/v3/re ... properties

yes, u r correct, that is is the mistake done in mapping file, but as per the naming conventions given in data base side, (which is already created),
ex:- in class_definition table i have column like class_id_pk(primary key), which is reference to foreigh key of another table in state_classes like class_id_fk, which the both columns are same, but in hibernate when it is mapping it is treating both the columns has different, i need to tell that column on both tables are same, is their is not another solution rather then keeping hbm2ddl update=false.....


thanq,

Sorry, I'm not sure I understand your problem. Could you explain it again ?

having two talbes in db like: ---

class_definition

class_id_pk | integer |
class_name | character varying(200) |
class_description | character varying(200) |
Indexes: class_id_pk primary key btree (class_id_pk),

state_classes

state_classes_id_pk | integer | not null
state_id_fk | integer | not null
class_id_fk | integer | not null
Indexes: state_classes_pkey primary key btree (state_classes_id_pk)
Foreign Key constraints: fk_state_id FOREIGN KEY (state_id_fk) REFERENCES state_definition(state_id) ON UPDATE NO ACTION ON DELETE NO ACTION,
class_id_fk FOREIGN KEY (class_id_fk) REFERENCES class_definition(class_id_pk) ON UPDATE NO ACTION ON DELETE NO ACTION

In the above table class_id_fk is a foreign key for class_definition(class_id_pk), these two coumns are same, if we take class_id as column in tables, hibernate will not create any extra column in db, otherwise it creates an a extra column in state_classes with class_id_pk . which is unnecessary,,
to avoid this extra column, is their any attribute, is their


thanq.

I guess I begin understanding your case. If I'm right, there's no problem to do it with Hibernate.

Though I'm not completely sure:
you say you have two columns that are the same??? So, you don't have two columns, you have only one that is mapped more than once, that should be. Could you precise what you mean by "they are the same"?

Please maybe also show the DDL you should have and the mapping you have at the moment.

CREATE TABLE class_definition (
class_id_pk integer DEFAULT nextval('class_id_pk_seq'::text) NOT NULL,
class_name character varying(200),
class_description character varying(200)
);


INSERT INTO class_definition VALUES (1,'NonWriteAclass', 'NonWriteAclass 1');
INSERT INTO class_definition VALUES (2,'NonWriteBclass', 'NonWriteBclass 1');
INSERT INTO class_definition VALUES (3,'vegetables', 'name of vegetables');
INSERT INTO class_definition VALUES (4,'test2', 'testdesc2');
INSERT INTO class_definition VALUES (5,'Pallet', 'Pallet');


CREATE TABLE state_classes (
state_classes_id_pk
state_id_fk integer,
class_id_fk integer
);

INSERT INTO state_classes VALUES (1,3007, 1);
INSERT INTO state_classes VALUES (2,3007, 2);
INSERT INTO state_classes VALUES (3,3009, 2);
INSERT INTO state_classes VALUES (4,3009, 1);
INSERT INTO state_classes VALUES (5,3013, 1);


class_definition.hbm.xml

<hibernate-mapping>
<class name="com.skandsoft.setu.pojos.classdefinition.ClassDefinition" table="class_definition" >

<id name="classIdPk" type="int" unsaved-value="null">
<column name="class_id_pk" not-null="true"/>
<generator class="org.hibernate.id.Assigned"></generator>
</id>

<property name="className" column="class_name" type="string" unique="true" access="field" />
<property name="classDescription" column="class_description" type="string" />

<set name="stateClasses" inverse="true" cascade="all">
<key>
<column name="class_id_pk" />
</key>
<one-to-many class="com.skandsoft.setu.pojos.stateclasses.StateClasses"/>
</set>

state_classes.hbm.xml
<hibernate-mapping>

<class name="com.skandsoft.setu.pojos.stateclasses.StateClasses" table="state_classes">

<id name="stateClassesIdPk" type="java.lang.Integer" unsaved-value="null" >
<column name="state_classes_id_pk" not-null="true"/>
<generator class="org.hibernate.id.Assigned"></generator>
</id>

<many-to-one name="classDefinition" class="com.skandsoft.setu.pojos.classdefinition.ClassDefinition" not-null="true" column="class_id_fk" foreign-key="class_id_fk" cascade="all" />


</class>
</hibernate-mapping>





when we run session factory, it creates class_id_pk column in state_classes table db... which i dont want to map. becoz it is already have column with class_id_fk which is same..but i should be keep in hibernate.cfg.xml with attribute like <property name="hibernate.hbm2ddl.auto">
update
</property becoz i should update some columns...

tankq..
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