questions: how much you are paying for each null in the B-refObj ? are you working for your RDBMS or your RDBMS should work for you ?
If your RDBMS has so many problems because a null in a column, throws it to the trash or creates an issue for the RDBMS-issue-tracker. 2010/1/27 Dana Efros <[email protected]> > The difference is that I don't have a many to many relationship. A "B" > entities can have only one "A" object > > On Jan 27, 5:14 pm, Shadowboxer <[email protected]> wrote: > > Hi, > > > > I have something similar in my web app. I did it like this: > > > > Class A mapping: > > > > <?xml version="1.0" encoding="utf-8" ?> > > <hibernate-mapping xmlns="urn:nhibernate-mapping-2.2"> > > <class name="A" table="table_A" > > > > > <id name="Code" type="Int32" > > > <column name="id" sql-type="integer" not-null="true" > > unique="true" /> > > <generator class="identity" /> > > </id> > > <property name="Name" type="String"> > > <column name="name" length="100" sql-type="varchar" not- > > null="true" /> > > </property> > > > > <set name="B" lazy="true" cascade="save-update" table="table_AB"> > > <key column="idA" /> > > <many-to-many class="B" column="idB"/> > > </set> > > > > </class> > > </hibernate-mapping> > > > > Class B mapping: > > > > <?xml version="1.0" encoding="utf-8" ?> > > <hibernate-mapping xmlns="urn:nhibernate-mapping-2.2"> > > <class name="B" table="table_B" > > > <id name="Code" type="Int32"> > > <column name="id" sql-type="integer" not-null="true" > > unique="true" /> > > <generator class="identity" /> > > </id> > > > > <property name="Name" type="String"> > > <column name="name" length="100" sql-type="varchar" not- > > null="true" /> > > </property> > > > > <set name="A" lazy="true" cascade="save-update" table="table_AB"> > > <key column="idB"/> > > <many-to-many class="A" column="idA"/> > > </set> > > > > </class> > > </hibernate-mapping> > > > > Hope it helps > > > > On Jan 27, 10:49 am, Dana Efros <[email protected]> wrote: > > > > > Hi. I have to 2 entities: > > > > > class A{ > > > int id; > > > string name;} > > > > > class B{ > > > int id; > > > A refObj; > > > string name;} > > > > > How can I map this 2 classes so I will have 3 tables: > > > table A with 2 columns: id and name > > > table B with 2 columns: id and name > > > table AB with 2 columns: idA and idB (idB is unique) > > > > > In the AB table I need to have a row only when refObj will not be > > > null.The field refObj from the B entity will have values only > > > occasionally and I don't want to have a column in the B table with > > > null value for almost all the rows > > > > > With a many to many relations I know how, but with a reference ... > > > Thanks > > -- > You received this message because you are subscribed to the Google Groups > "nhusers" group. > To post to this group, send email to [email protected]. > To unsubscribe from this group, send email to > [email protected]<nhusers%[email protected]> > . > For more options, visit this group at > http://groups.google.com/group/nhusers?hl=en. > > -- Fabio Maulo -- You received this message because you are subscribed to the Google Groups "nhusers" group. To post to this group, send email to [email protected]. To unsubscribe from this group, send email to [email protected]. For more options, visit this group at http://groups.google.com/group/nhusers?hl=en.
