hibernate ORM related

一、单向关联（unidirectional associations）：

1.1.1 Many-to-one

Employee.hbm.xml

<class name="Employee" table="T_EMPLOYEE">

    <id name="employee_Id" column="EMPLOYEE_ID">

        <generator class="native"/>

    </id>

    <many-to-one name="department" column="DEPARTMENT_ID" not-null="true"/>

</class>

Department.hbm.xml

<class name="Department" table="T_DEPARTMENT"> <id name="department_Id" column="DEPARTMENT_ID"> <generator class="native"/> </id> </class> create table EMPLOYEE(employee_Id bigint not null primary key,department_Id bigint not null) create table DEPARTMENT(department_Id bigint not null primary key)

?单向的<many-to-one>里没有指明class

1.1.2 One-t-one

1>单向一对一和单向多对一区别就是Unique这个属性,基于外键

<class name="Employee" table="T_EMPLOYEE">

    <id name="employee_Id" column="EMPLOYEE_ID">

        <generator class="native"/>

    </id>

    <many-to-one name="department"

                           column="DEPARTMENT_ID"

                           unique="true"

                           not-null="true"/>

</class>

<class name="Department" table="T_DEPARTMENT">

    <id name="department_Id" column="DEPARTMENT_ID">

        <generator class="native"/>

    </id>

</class>

2>基于主键

<class name="Person" table="Person">

    <id name="Person_Id" column="PERSON_ID">

        <generator class="native"/>

    </id>

</class>

<class name="Card" table="Card">

    <id name="Card_Id" column="PERSON_ID">

        <generator class="foreign">

            <param name="property">person</param>

        </generator>

    </id>

    <one-to-one name="person" constrained="true"/>

</class>

create table Person ( PERSON_ID  bigint not null primary key )

create table Card( PERSON_ID bigint not null primary key )

? one-to-one 没有column和table属性，有class属性，name标志？，如何指定person对象。

1.1.3 One-to-many

<class name="Department">

    <id name="department_Id" column="DEPARTMENT_ID">

        <generator class="native"/>

    </id>

    <set name="employee">

        <key column="DEPARTMENT_ID"

            not-null="true"/>

        <one-to-many class="Employee"/>

    </set>

</class>

<class name="Employee">

    <id name="employee_Id" column="EMPLOYEE_ID">

        <generator class="native"/>

    </id>

</class>

create table Department( department_Id bigint not null primary key )

create table Emplyee( employee_Id bigint not null primary key, personId bigint not null )

you should instead use a join table for this kind of asociation

二、单向关联with join table

2.1.1 One-to-many

<class name="Department">

    <id name="department_Id" column="DEPARTMENT_ID">

        <generator class="native"/>

    </id>

    <set name="employees" table="DepartmetEmployee">

        <key column="DEPARTMENT_ID"/>

        <many-to-many column="EMPLOYEE_ID"

            unique="true"

            class="Employee"/>

    </set>

</class>

<class name="Employee">

    <id name="employee_Id" column="EMPLOYEE_ID">

        <generator class="native"/>

    </id>

</class>

create table Department( Department_Id bigint not null primary key )

create table DepartmentEmployee(Department_Id bigint not null, employee_Id bigint not null primary key ) 
create table Employee( employee_Id bigint not null primary key )

specifying unique="ture" change multiplicity from many-to-many to one-to-many.

2.1.2.Many-to-one

<class name="Department">

    <id name="department_Id" column="DEPARTMENT_ID">

        <generator class="native"/>

    </id>

</class>

<class name="Employee">

    <id name="employee_Id" column="EMPLOYEE_ID">

        <generator class="native"/>

    </id>

    <join table="EmployeeDepartment"

        optional="true">

        <key column="EMPLOYEE_ID" unique="true"/>

        <many-to-one name="department"

            column="DEPARTMENT_ID"

            not-null="true"/>

    </join>

</class>

2.1.3 One-to-one

<class name="Person" table="Person">

    <id name="Person_Id" column="PERSON_ID">

        <generator class="native"/>

    </id>

    <join table="PersonCard"

        optional="true">

        <key column="PERSON_ID"

            unique="true"/>

        <many-to-one name="card"

            column="CARD_ID"

            not-null="true"

            unique="true"/>

       </join>

</class>

<class name="Card" table="Card">

    <id name="Card_Id" column="CARD_ID">

        <generator class="native"/>

    </id>

    <one-to-one name="person" constrained="true"/>

</class>

create table Person ( PERSON_ID  bigint not null primary key )

create table PersonCard ( PERSON_ID bigint not null primary key, CARD_ID bigint not null unique )

create table Card( CARD_ID bigint not null primary key )

2.1.4.Many-to-many

<class name="Person">

    <id name="id" column="personId">

        <generator class="native"/>

    </id>

    <set name="addresses" table="PersonAddress">

        <key column="personId"/>

        <many-to-many column="addressId"

            class="Address"/>

    </set>

</class>

<class name="Address">

    <id name="id" column="addressId">

        <generator class="native"/>

    </id>

</class>

create table Person ( personId bigint not null primary key )

create table PersonAddress ( personId bigint not null, addressId bigint not null, primary key (personId, addressId) )

create table Address ( addressId bigint not null primary key )

三、双向关联(Bidirectional associations)

3.1.1.one-to-one

<class name="Person">

    <id name="id" column="personId">

        <generator class="native"/>

    </id>

    <one-to-one name="address"/>

</class>

<class name="Address">

    <id name="id" column="personId">

        <generator class="foreign">

            <param name="property">person</param>

        </generator>

    </id>

    <one-to-one name="person"

        constrained="true"/>

</class>

create table Person ( personId bigint not null primary key )

create table Address ( personId bigint not null primary key )

<class name="Person">

    <id name="id" column="personId">

        <generator class="native"/>

    </id>

    <many-to-one name="address"

        column="addressId"

        unique="true"

        not-null="true"/>

</class>

<class name="Address">

    <id name="id" column="addressId">

        <generator class="native"/>

    </id>

   <one-to-one name="person"

        property-ref="address"/>

</class>

create table Person ( personId bigint not null primary key, addressId bigint not null unique )

create table Address ( addressId bigint not null primary key )

3.1.2.one-to-many/many-to-one：

<class name="Person">

    <id name="id" column="personId">

        <generator class="native"/>

    </id>

    <many-to-one name="address"

        column="addressId"

        not-null="true"/>

</class>

<class name="Address">

    <id name="id" column="addressId">

        <generator class="native"/>

    </id>

    <set name="people" inverse="true">

        <key column="addressId"/>

        <one-to-many class="Person"/>

    </set>

</class>

create table Person ( personId bigint not null primary key, addressId bigint not null )

create table Address ( addressId bigint not null primary key )

<class name="Person">

   <id name="id"/>

   ...

   <many-to-one name="address"

      column="addressId"

      not-null="true"

      insert="false"

      update="false"/>

</class>

<class name="Address">

   <id name="id"/>

   ...

   <list name="people">

      <key column="addressId" not-null="true"/>

      <list-index column="peopleIdx"/>

      <one-to-many class="Person"/>

   </list>

</class>

四、双向关联with join table

4.1.1.one-to-many/many-to-one

4.1.2.one-to-one

4.1.3.many-to-many

巴特西

hibernate ORM related

最新文章

热门文章