javax.persistence
Annotation Type Column

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

Is used to specify a mapped column for a persistent property or field. If no Column annotation is specified, the default values are applied.

Examples:

 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

java.lang.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.
java.lang.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.
java.lang.String	table (Optional) The name of the table that contains the column.
boolean	unique (Optional) Whether the property is a unique key.
boolean	updatable (Optional) Whether the column is included in SQL UPDATE statements generated by the persistence provider.

name

public abstract java.lang.String name

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

Default:

""

unique

public abstract boolean unique

(Optional) Whether the property 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 is only a single field. This constraint applies in addition to any constraint entailed by primary key mapping and to constraints specified at the table level.

Default:

false

nullable

public abstract boolean nullable

(Optional) Whether the database column is nullable.

Default:

true

insertable

public abstract boolean insertable

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

Default:

true

updatable

public abstract boolean updatable

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

Default:

true

columnDefinition

public abstract java.lang.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.

Default:

""

table

public abstract java.lang.String table

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

Default:

""

length

public abstract int length

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

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.

Default:

0

scale

public abstract int scale

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

Default:

0