Column (Java EE 5 SDK) - Java Platform, Enterprise Edition v5.0 API Specifications

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SUMMARY: REQUIRED | OPTIONAL

DETAIL: ELEMENT

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

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 property is a unique key.

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

Optional Element Summary
`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 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 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 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 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