javax.persistence

Annotation Type Column

@Target(value={METHOD,FIELD})
 @Retention(value=RUNTIME)
public @interface Column

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:

Java Persistence 1.0

Optional Element Summary

Optional Elements

Modifier and Type	Optional Element and Description
String	columnDefinition (Optional) The SQL fragment that is used when generating the DDL for the column.
boolean	insertable (Optional) Whether the column is included in SQL INSERT statements generated by the persistence provider.
int	length (Optional) The column length.
String	name (Optional) The name of the column.
boolean	nullable (Optional) Whether the database column is nullable.
int	precision (Optional) The precision for a decimal (exact numeric) column.
int	scale (Optional) The scale for a decimal (exact numeric) column.
String	table (Optional) The name of the table that contains the column.
boolean	unique (Optional) Whether the column is a unique key.
boolean	updatable (Optional) Whether the column is included in SQL UPDATE statements generated by the persistence provider.

Element Detail

name

public abstract String name

(Optional) The name of the column. Defaults to the property or field name.

Returns:

name

Default:

""

unique

public abstract boolean unique

(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.

Returns:

whether this is unique

Default:

false

nullable

public abstract boolean nullable

(Optional) Whether the database column is nullable.

Returns:

whether this is nullable

Default:

true

insertable

public abstract boolean insertable

(Optional) Whether the column is included in SQL INSERT statements generated by the persistence provider.

Returns:

whether this is insertable

Default:

true

updatable

public abstract boolean updatable

(Optional) Whether the column is included in SQL UPDATE statements generated by the persistence provider.

Returns:

whether this is updateable

Default:

true

columnDefinition

public abstract String columnDefinition

(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.

Returns:

column def

Default:

""

table

public abstract String table

(Optional) The name of the table that contains the column. If absent the column is assumed to be in the primary table.

Returns:

table

Default:

""

length

public abstract int length

(Optional) The column length. (Applies only if a string-valued column is used.)

Returns:

length

Default:

255

precision

public abstract int precision

(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.

Returns:

precision

Default:

0

scale

public abstract int scale

(Optional) The scale for a decimal (exact numeric) column. (Applies only if a decimal column is used.)

Returns:

scale

Default:

0