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python sqlalchemy在元组数据结构中插入多行

2019-10-09 23:00:15??阅读:545??来源: 互联网

标签:python?tuples?sqlalchemy?sql-insert?bulkinsert


我一直在研究如何在数据库中插入具有7个元素(列)的约500个元组(行)的列表.我已经阅读了关于stackoverflow的各种帖子以及其他论坛.我发现了以下内容,并建议使用“ executemany()”方法,但对我来说不清楚.我是否需要将对象从元组转换为字典?问题是我没有数据结构的name:value类型.

How to use SQLAlchemy to dump an SQL file from query expressions to bulk-insert into a DBMS?

Here is an example:

engine = create_engine('sqlite:///:memory:', echo=True)
metadata = MetaData()
hockey= Table('hockey', metadata, 
    Column('team', String(16), primary_key=True),
    Column('jersey_colour', String(16)),
    Column('stadium', String(32)),
    Column('goals', Integer),
    Column('date', Date, primary_key=True),
    Column('assists', Integer))

>>>data[0]
[(u'Maple Leafs', u'Blue', u'Air Canada Center', 151, '2013-03-25', 301)]

编辑:

我尝试了如下所述的解决方案(Sqlalchemy core, insert multiple rows from a tuple instead of dict):

markers = ','.join('?' * len(data[0]))
ins = 'INSERT INTO {tablename} VALUES ({markers})'
ins = ins.format(tablename=hockey.name, markers=markers)

>>str(ins)
'INSERT INTO hockey VALUES (?,?,?,?,?,?)'

conn = engine.connect()
result = conn.execute(ins, data)

In [59]: result = conn.execute(ins, data)
2013-03-26 07:29:28,371 INFO sqlalchemy.engine.base.Engine INSERT INTO hockey VALUES (?,?,?,?,?,?)
2013-03-26 07:29:28,371 INFO sqlalchemy.engine.base.Engine (u'Maple Leafs', u'Blue', u'Air Canada Center', 151, '2013-03-25', 301)
2013-03-26 07:29:28,371 INFO sqlalchemy.engine.base.Engine ROLLBACK
---------------------------------------------------------------------------
OperationalError                          Traceback (most recent call last)
 in ()
----> 1 result = conn.execute(ins, data)

/usr/lib/python2.7/site-packages/sqlalchemy/engine/base.pyc in execute(self, object, *multiparams, **params)
    662                                                 object,
    663                                                 multiparams,
--> 664                                                 params)
    665         else:
    666             raise exc.InvalidRequestError(

/usr/lib/python2.7/site-packages/sqlalchemy/engine/base.pyc in _execute_text(self, statement, multiparams, params)
    806             statement,
    807             parameters,
--> 808             statement, parameters
    809         )
    810         if self._has_events:

/usr/lib/python2.7/site-packages/sqlalchemy/engine/base.pyc in _execute_context(self, dialect, constructor, statement, parameters, *args)
    876                                 parameters,
    877                                 cursor,
--> 878                                 context)
    879             raise
    880

/usr/lib/python2.7/site-packages/sqlalchemy/engine/base.pyc in _execute_context(self, dialect, constructor, statement, parameters, *args)
    869                                     statement,
    870                                     parameters,
--> 871                                     context)
    872         except Exception, e:
    873             self._handle_dbapi_exception(

/usr/lib/python2.7/site-packages/sqlalchemy/engine/default.pyc in do_execute(self, cursor, statement, parameters, context)
    318
    319     def do_execute(self, cursor, statement, parameters, context=None):
--> 320         cursor.execute(statement, parameters)
    321
    322     def do_execute_no_params(self, cursor, statement, context=None):

OperationalError: (OperationalError) near "hockey": syntax error 'INSERT INTO hockey VALUES (?,?,?,?,?,?)' (u'Maple Leafs', u'Blue', u'Air Canada Center', 151, '2013-03-25', 301)

出现错误:

  OperationalError: (OperationalError) near "hockey": syntax error 'INSERT INTO hockey VALUES (?,?,?,?,?,?)' (u'Maple Leafs', u'Blue', u'Air Canada Center', 151, '2013-03-25', 301)

解决方法:

好吧,我做了以下工作:

column_names = tuple(c.name for c in hockey.c)

>>>column_names
('team', 'jersey_colour', 'stadium', 'goals', 'date', 'assists')

final = [dict(zip(column_names,x)) for x in data]

上面为每行或每行创建了一个字典列表.这应该可以工作,但是当我运行时出现以下错误:

>>>conn.execute(ins, final)

SQLite Date type only accepts Python date objects as input.

无论如何,这是我需要研究的另一个问题.就是说,我正在回答并接受这个问题,因为上面的词典应该起作用.



标签:python,tuples,sqlalchemy,sql-insert,bulkinsert

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