1.如何实现SQLAlchemy的升序降序查询?
源码：asc = public_factory(UnaryExpression._create_asc, “.expression.asc”)
desc = public_factory(UnaryExpression._create_desc, “.expression.desc”)
例子：
SQL语句：select * from user order by age desc
Python代码：users = User.query.order_by(db.desc(User.age)).all()
2.如何实现SQLAlchemy的Select like的用法?
源码：def like(self, other, escape=None):
“””Implement the “like“ operator.
In a column context, produces the clause “a LIKE other“.
E.g.::
select([sometable]).where(sometable.c.column.like(“%foobar%”))
:param other: expression to be compared
:param escape: optional escape character, renders the “ESCAPE“
keyword, e.g.::
somecolumn.like(“foo/%bar”, escape=”/”)
.. seealso::
:meth:`.ColumnOperators.ilike`
“””
return self.operate(like_op, other, escape=escape)
例子：
SQL语句：select * from user where username like ‘%john%’
Python代码：users = User.query.filter(Product.username.like(‘%john%’)).all()
总结：其实这些如果能看得懂源代码的英语以及懂得SQL语句，基本可以通过查阅源码解决以上类似的问题。