为什么返回元组？

Question

I have the following:

tableNumber = session.query(TABLE.TABLESNUMBER).filter_by(TABLESID=self.TABLESID).first()         
return str(tableNumber)

This is my TABLE class:

class TABLE(Base):

    ....   

    TABLESID = Column(Integer, primary_key=True)
    TABLESNUMBER = Column(Integer, nullable=False)

    ...

This is the output I am receiving:

(1L,)

In my mySQL database , all both values above are represented as ints .

I would just like 1 to be returned.

Answer 1

query().first() returns the first row. That's why a tuple is being returned. The query does not care that in the first row there is only 1 value, resulting in a tuple of length 1.

If you're sure the query will return only 1 scalar value, you can use scalar() instead of first() . Please read up the linked documentation.

edit: To get the first value in the first returned tuple, when the query may return multiple rows, you can either add order_by(...).limit(1) to the query and then use scalar() , or get the first row and and then explicitly convert the tuple to an int.

Answer 2

first() and all() return 'tuple'

So,
session.query(TABLE.TABLESNUMBER).filter_by(TABLESID=self.TABLESID).first() returns its tuple including 'TABLESNUMBER'

If you want exactly one value (TABLESNUMBER)

You can use it. session.query(TABLE.TABLESNUMBER).filter_by(TABLESID=self.TABLESID).first().TABLESNUMBER