org.mayanjun.myjack.api.annotation

Annotation Type Column

@Retention(value=RUNTIME)
 @Target(value=FIELD)
public @interface Column

用来定义数据库类字段和数据库表字段之间的映射。 A Column used to annotate a field that mapped to a column of table in database

Since:

0.0.1

Author:

mayanjun(8/19/15)

Optional Element Summary

Optional Elements

Modifier and Type	Optional Element and Description
String	comment 字段注释信息 Specified the comment
String	defaultValue 定义默认值。如果默认值为空，则默认值去数据类型中定义的默认值。 Specified the default value to this column.
String	length 定义字段长度，内容和SQL DDL中的长度定义一样 Specifies the SQL DDL length expression
boolean	notNull 定义字段是否可为空 Specifies whether the NULL value be allowed on this column
String	referenceField 当一个@Table对象引用另一个@Table对象时，我们可以通过这个字段指定外键引用。 Specifies the reference field when a column field is referenced to an EntityBean.
DataType	type 数据类型 The data type of database
boolean	unsigned 如果是数字，定义是否是无符号数据类型 Specifies whether the numeric data type is unsigned
String	value 字段名称 The column name, by default uses the field name

Element Detail

value

public abstract String value

字段名称 The column name, by default uses the field name

Returns:

column name

Default:

""

type

public abstract DataType type

数据类型 The data type of database

Returns:

data type

Default:

org.mayanjun.myjack.api.enums.DataType.VARCHAR

unsigned

public abstract boolean unsigned

如果是数字，定义是否是无符号数据类型 Specifies whether the numeric data type is unsigned

Returns:

boolean

Default:

false

length

public abstract String length

定义字段长度，内容和SQL DDL中的长度定义一样 Specifies the SQL DDL length expression

Returns:

length definition

Default:

""

notNull

public abstract boolean notNull

定义字段是否可为空 Specifies whether the NULL value be allowed on this column

Returns:

true if null value not be allowed

Default:

true

defaultValue

public abstract String defaultValue

定义默认值。如果默认值为空，则默认值去数据类型中定义的默认值。 Specified the default value to this column. The default value defined in DataType will be used.

Returns:

the default value for this column

Default:

""

comment

public abstract String comment

字段注释信息 Specified the comment

Returns:

comments for column

Default:

""

referenceField

public abstract String referenceField

当一个@Table对象引用另一个@Table对象时，我们可以通过这个字段指定外键引用。 Specifies the reference field when a column field is referenced to an EntityBean. When the referenceField is specified, the query parse will generate a select field with 'AS' clause for this field. For example, consider the following declare:

     @Column(type = DataType.BIGINT, comment = "项目ID", referenceField = "id")
     private Subject subject;
 

the selected field will be: subject AS `subject.id`

Returns:

reference field name

Default:

""