实体类映射数据库，自动建表

@Column(name="price", nullable=false, precision = 23, scale = 6)
    private BigDecimal price;

    @Column(name="num" ,columnDefinition="int(9) default 2 comment '提现金额'")
    public int num;
    @Column(name="f_colum" ,columnDefinition="float(10,2)")
    public float fColum;