SQLalchemy 如何根据另一个表的日期从另一个表查询？

Question

So I'm trying to query the number of access attempts, failed and success, on a daily basis. These are the tables I have created.

class SystemLog(Base):
    __tablename__ = 'SystemLog'

    ID = Column(Integer, primary_key=True)
    Date = Column(Text)
    Time = Column(Text)
    PID = Column(Integer)
    Message = Column(Text)


class Messages(Base):
    __tablename__ = 'Messages'

    ID = Column(Integer, primary_key=True)
    Message = Column(Text)
    AccessType = Column(Text)
    IP = Column(Integer)

What I've tried:

test = session.query(SystemLog.Date, Messages.AccessType, func.count(Messages.AccessType))\
        .join(Messages).filter(SystemLog.ID==Messages.ID)\
        .group_by(SystemLog.Date, Messages.AccessType).all()

How a SystemLog row looks like:

How a Messages row looks like:

But this gives me an error saying i need to use an ON clause. There are a few things I am unsure about as well. Are my tables created correctly and how do I do a join?

That being said, I cannot put all the columns into 1 table. At the very least, AccessType and IP has to be on a separate table and Date, Time, PID and Message have to be in 1 table.

Answer 1

Based on the information in the comments:

• that there is a one-to-one relationship between the tables
• that the relationship between the two is that the contents of the message column in related rows is identical (implying each message is unique)

the query would look like this:

test = session.query(SystemLog.Date, Messages.AccessType, func.count(Messages.AccessType))\
              .join(Messages, SystemLog.message == Messages.message)\
              .group_by(SystemLog.Date, Messages.AccessType).all()

As far as the tables are concerned, I'd try to use more specific data types, for example Date should be a sqlalchemy.Date or sqlachemy.DateTime . And joining on a long string like message could be slow, ideally you'd join on an integer value.