JPA设置默认字段及其长度详解

@Target({ElementType.METHOD, ElementType.FIELD})
@Retention(RetentionPolicy.RUNTIME)
public @interface Column {
    String name() default "";

    boolean unique() default false;

    boolean nullable() default true;

    boolean insertable() default true;

    boolean updatable() default true;

    String columnDefinition() default "";

    String table() default "";

    int length() default 255;

    int precision() default 0;

    int scale() default 0;
}

@Column(name = “name”)
private String name;

@Column(name = “name”,length = 50)
private String name;

name varchar(50)

@Column(name = “name”,columnDefinition=“varchar(11) COMMENT ‘用户姓名'”)
private String name;

name varchar(11) COMMENT ‘用户姓名'

@Column(name = “name”,columnDefinition=“default ‘12345'”)
private String name;

create table user (id bigint not null, age integer, birth datetime(6), name default ‘12345', sex bit, primary key (id)) engine=InnoDB

@Column(name = “name”,columnDefinition=“default ‘12345'”,length = 25)
private String name;

create table user (id bigint not null, age integer, birth datetime(6), name default ‘12345', sex bit, primary key (id)) engine=InnoDB

   /**
     * (Optional) The SQL fragment that is used when 
     * generating the DDL for the column.
     * <p> Defaults to the generated SQL to create a
     * column of the inferred type.
     */
    String columnDefinition() default "";

/**
*（可选）在以下情况下使用的SQL片段：
*正在为列生成DDL。
*默认使用生成的SQL来创建推断类型的列。
*/

@Column(name = “name”,columnDefinition=" varchar(11) default ‘12345'",length = 25)
private String name;
create table user (id bigint not null, age integer, birth datetime(6), name varchar(11) default ‘12345', sex bit, primary key (id)) engine=InnoDB

@Column(name = “sex”)
private Boolean sex;

@Column(name = “sex”)
private boolean sex;

@Column(name = “sex”,length = 50)
private boolean sex;

create table user (id bigint not null, age integer, birth datetime(6), name varchar(255), sex bit, primary key (id)) engine=InnoDB

@Column(name = “sex”,columnDefinition = “bit(1) default 1”)
private boolean sex;

@Column(name = "birth")
private Date birth;

	@Temporal(TemporalType.DATE)
	@Column(name = "birth")
	private Date birth;

@Column(name = “age”,scale = 2)
private int age;

@Column(name = “age”,scale = 2)
private float age;

@Column(name = “age”,precision = 5,scale = 2)
private float age;

@Column(name = “age”,columnDefinition = “decimal(5,2)”)
private double age;

	/**
	 * 备注
	 */
   	@Basic(fetch = FetchType.LAZY)
	@Type(type = "text")
	@Lob
	@Column(name = "remark")
	private String remark;