@Column

From CauchoWiki

The @Column annotation specifies the name of the database column for a persistent field or property. If the @Column is not specified the field name is used instead.

 @Entity
 public class TestBean {
    @Id
    @Column(name="t_id)
    public int getId()
     ...
 }

[edit] Annotation Definition

 public @interface Column {
     String name() default "";
     boolean unique() default false;
     boolean nullable() default true;
     boolean insertable() default true;
     boolean updatable() default true;
     boolean columnDefinition() default "";
     String table() default "";
     int length() default 255;
     int precision() default 0;
     int scale() default 0;
 }

attribute	description	default
name	the database column name	the property name
unique	if true, the column is UNIQUE	false
nullable	if false, the column is NOT NULL	true
insertable	if true, the column is filled when the bean is created	true
updatable	if true, the column is updated when the bean changes	true
columnDefinition	SQL code for the column type at creation
table	database table containing the column, e.g. a @SecondaryTable	the entity's main table
length	size of the column at table creation	255
precision	precision of numeric types at table creation	0
scale	scale of numeric types at table creation	0

Many applications will only use the name attribute. Most of the other annotations are only used if create-database-schema is true and the table does not exist in the database.

[edit] Related annotations

• @Basic annotation for a primitive-valued column
• @Id annotation for a primary key
• @Table specifies database table
• @JoinColumn specifies column names for foreign keys

[edit] Example

 @Entity
 public class TestBean {
     @Id
     @Column(name="t_id")
     private int id;

     @Basic
     @Column(name="t_data",length=32)
     private String data;
 }

 create table TESTBEAN (
     t_id integer primary key,

     t_data varchar(32)
 )