com.easycodebox.common.jpa

注释类型 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",
         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; }

 

从以下版本开始:

Java Persistence 1.0

可选元素概要

可选元素

限定符和类型	可选元素和说明
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.

元素详细资料

name

public abstract String name

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

默认值:

""

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.

默认值:

false

nullable

public abstract boolean nullable

(Optional) Whether the database column is nullable.

默认值:

true

insertable

public abstract boolean insertable

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

默认值:

true

updatable

public abstract boolean updatable

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

默认值:

true

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.

默认值:

""

length

public abstract int length

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

默认值:

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.

默认值:

0

scale

public abstract int scale

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

默认值:

0