Home » JPA » Annotations » Mapping (ORM) » Column

Note: This ORM/SQL annotation is silently ignored by ObjectDB

452 words

javax.persistence.Column - JPA annotation

javax.persistence
Annotation Column

Target:
Fields (including property get methods)
Is used to specify the mapped column for a persistent property or field. If no Column annotation is specified, the default values apply.

Example 1:

    @Column(name="DESC", nullable=false, length=512)
    public String getDescription() { return description; }

Example 2:

    @Column(name="DESC",
            columnDefinition="CLOB NOT NULL",
            table="EMP_DETAIL")
    @Lob
    public String getDescription() { return description; }

Example 3:

    @Column(name="ORDER_COST", updatable=false, precision=12, scale=2)
    public BigDecimal getCost() { return cost; }
Since:
JPA 1.0
String columnDefinition
(Optional) The SQL fragment that is used when generating the DDL for the column.
(Optional) The SQL fragment that is used when generating the DDL for the column.

Defaults to the generated SQL to create a column of the inferred type.

Default value:
""
Since:
JPA 1.0
boolean insertable
(Optional) Whether the column is included in SQL INSERT statements generated by the persistence provider.
(Optional) Whether the column is included in SQL INSERT statements generated by the persistence provider.
Default value:
true
Since:
JPA 1.0
int length
(Optional) The column length.
(Optional) The column length. (Applies only if a string-valued column is used.)
Default value:
255
Since:
JPA 1.0
String name
(Optional) The name of the column.
(Optional) The name of the column. Defaults to the property or field name.
Default value:
""
Since:
JPA 1.0
boolean nullable
(Optional) Whether the database column is nullable.
(Optional) Whether the database column is nullable.
Default value:
true
Since:
JPA 1.0
int precision
(Optional) The precision for a decimal (exact numeric) column.
(Optional) The precision for a decimal (exact numeric) column. (Applies only if a decimal column is used.) Value must be set by developer if used when generating the DDL for the column.
Default value:
0
Since:
JPA 1.0
int scale
(Optional) The scale for a decimal (exact numeric) column.
(Optional) The scale for a decimal (exact numeric) column. (Applies only if a decimal column is used.)
Default value:
0
Since:
JPA 1.0
String table
(Optional) The name of the table that contains the column.
(Optional) The name of the table that contains the column. If absent the column is assumed to be in the primary table.
Default value:
""
Since:
JPA 1.0
boolean unique
(Optional) Whether the column is a unique key.
(Optional) Whether the column is a unique key. This is a shortcut for the UniqueConstraint annotation at the table level and is useful for when the unique key constraint corresponds to only a single column. This constraint applies in addition to any constraint entailed by primary key mapping and to constraints specified at the table level.
Default value:
false
Since:
JPA 1.0
boolean updatable
(Optional) Whether the column is included in SQL UPDATE statements generated by the persistence provider.
(Optional) Whether the column is included in SQL UPDATE statements generated by the persistence provider.
Default value:
true
Since:
JPA 1.0
This documentation page is derived (with some adjustments) from the open source JPA 2 RI (EclipseLink)
and is available under the terms of the Eclipse Public License, v. 1.0 and Eclipse Distribution License, v. 1.0.
Object Relational Mapping (ORM) JPA 2 providers include Hibernate, EclipseLink, TopLink, OpenJPA and DataNucleus.
Object DB is not an ORM JPA implementation but an Object Database for Java with built in JPA 2 support.