EclipseLink/UserGuide/JPA/Basic JPA Development/Mapping/Basic Mappings/Column

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• @Column

@Column

Use the @Column annotation to specify a mapped column for a persistent property or field. If no Column annotation is specified, the default values, as shown in the table below, apply.

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For more information, see Section 11.1.9 "Column Annotation" in the JPA Specification.

@Column Annotation Attributes

Attribute	Description	Default	Required?
name	The name of the column.	The property or field name.	No
unique	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.	false	No
nullable	Whether the database column is nullable.	true	No
insertable	Whether the column is included in SQL INSERT statements generated by the persistence provider.	true	No
updatable	Whether the column is included in SQL UPDATE statements generated by the persistence provider.	true	No
columnDefinition	The SQL fragment that is used when generating the DDL for the column.	Generated DDL to create a column of the inferred type.	No
table	The name of the table that contains the column. If absent the column is assumed to be in the primary table for the mapped object.	Column is in primary table.	No
length	The column length. (Applies only if a string-valued column is used.)	255	No
precision	The precision for a decimal (exact numeric) column. (Applies only if a decimal column is used.)	0 (Value must be set by developer.)	No
scale	The scale for a decimal (exact numeric) column. (Applies only if a decimal column is used.)	0	No

The following example shows how to use the @Column annotation, with values to override the defaults for updatable, precision, and scale.

Example: @Column Annotation

@Column(name="ORDER_COST", updatable=false, precision=12, scale=2)
public BigDecimal getCost() { return cost; }

Version: DRAFT
Other versions...

@Transient	Basic Mappings	Default Conversions and Converters
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