都可看做是where但用法不一样

filter_by

1question = Questions.query.filter_by(id=1).first()

filter

1question = Questions.query.filter(Questions.id==1).first()

其实就是= 与==还有是否带类名的区别
如果要select * from questions where id < 5
这时只能使用filter

1questions = Questions.query.filter(Questions.id < 5).all()

多个条件

1question = Questions.query.filter_by(name='hello',id=5).first()
2# 或者
3question = Questions.query.filter(Questions.name=='hello',Questions.id==5).first()