Hibernate annoation (Eight association mappings)

Onetoone: One-way

1, primary Key association:

Use @onetoone in association

SQL statements: (class code See the same code as before)

Java code

create　table　A　(id　integer　not　null　auto_increment,　aname　varchar(255),　b_id　integer,　primary　key　(id))
create　table　B　(id　integer　not　null　auto_increment,　bname　varchar(255),　primary　key　(id))
alter　table　A　add　index　FK41FCD34905　(b_id),　add　constraint　FK41FCD34905　foreign　key　(b_id)　references　B　(id)　

Can be associated by using @primarykeyjoincolumn

2 bidirectional:

Used in the associated party

@OneToOne (Cascade=cascadetype.all)

@JoinColumn (name= "B")

Used by the associated party

@OneToOne (mappedby= "B")

Final sql:

Java codecreate　table　A　(id　integer　not　null　auto_increment,　aname　varchar(255),　b　integer,　primary　key　(id))
create　table　B　(id　integer　not　null　auto_increment,　bname　varchar(255),　primary　key　(id))
alter　table　A　add　index　FK41FCA54B4F　(b),　add　constraint　FK41FCA54B4F　foreign　key　(b)　references　B　(id)

If you do not write

@OneToOne (mappedby= "B") will also generate a field in the association

Final code:

Java code

create　table　A　(id　integer　not　null　auto_increment,　aname　varchar(255),　i_id　integer,　primary　key　(id))
create　table　B　(id　integer　not　null　auto_increment,　bname　varchar(255),　a_id　integer,　primary　key　(id))
alter　table　A　add　index　FK41FCD6779E　(i_id),　add　constraint　FK41FCD6779E　foreign　key　(i_id)　references　B　(id)
alter　table　B　add　index　FK42FCD2D4A5　(a_id),　add　constraint　FK42FCD2D4A5　foreign　key　(a_id)　references　A　(id)

If you do not write @joincolumn (name= "B"), the default is the associated property name + underscore +id

Final sql:

Java code

create　table　A　(id　integer　not　null　auto_increment,　aname　varchar(255),　b_id　integer,　primary　key　(id))
create　table　B　(id　integer　not　null　auto_increment,　bname　varchar(255),　primary　key　(id))
alter　table　A　add　index　FK41FCD34905　(b_id),　add　constraint　FK41FCD34905　foreign　key　(b_id)　references　B　(id)

You can use @joincolumn (referencedcolumnname= "bname") to let the primary association not associate the primary key that is placed by the association

Final SQL

Java code

create　table　A　(id　integer　not　null　auto_increment,　aname　varchar(255),　b_bname　varchar(255),　primary　key　(id))
create　table　B　(id　integer　not　null　auto_increment,　bname　varchar(255),　primary　key　(id),　unique　(bname))
alter　table　A　add　index　FK41E47CD6BD　(b_bname),　add　constraint　FK41E47CD6BD　foreign　key　(b_bname)　references　B　(bname)