正确生成浮点型的方法，解决sqlachemy Float浮点型的坑，生成float类型时，长度和精度均为0，导致查询不到结果！

from sqlalchemy import Float,Column
price = Column(Float,default=0.00)

from sqlalchemy import Column,Float
from sqlalchemy.dialects.mysql import FLOAT


class TestTable(db.Model):
    __tablename__ = 'my_test_table'
    float_1 = Column(FLOAT(length=10, precision=2))
    float_2 = Column(Float(10,2))
    float_3 = Column(Float(as_decimal=True))
    float_4 = Column(Float(precision=10, scale=2),default=0.00)

from sqlalchemy.dialects.mysql import FLOAT

float_5 = Column(FLOAT(precision=10, scale=2))