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EclipseLink/UserGuide/JPA/Basic JPA Development/Mapping/Basic Mappings/Column
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@Column
Use the Column annotation to specify a mapped column for a persistent property or field.
.For more information, see Section 11.1.9 "Column Annotation" in the JPA Specification.
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 SQL 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 to ....
@Column(name="ORDER_COST", updatable=false, precision=12, scale=2) public BigDecimal getCost() { return cost; }