I am having trouble writing a sqlalchemy query which selects all rows
where a field equals the max for that field, eg
q =
session.query(Snapshot).filter(Snapshot.totalqty==func.max(Snapshot.totalqty))
When I try and get the results of the query, I get the error below.
How should I use func.max here?
__version__ = 0.5.0rc3
In [54]: len(q.all())
------------------------------------------------------------
Traceback (most recent call last):
File "<ipython console>", line 1, in ?
File
"/home/titan/johnh/dev/lib/python2.4/site-packages/SQLAlchemy-0.5.0rc3dev_r5205-py2.4.egg/sqlalchemy/orm/query.py",
line 994, in all
return list(self)
File
"/home/titan/johnh/dev/lib/python2.4/site-packages/SQLAlchemy-0.5.0rc3dev_r5205-py2.4.egg/sqlalchemy/orm/query.py",
line 1082, in __iter__
return self._execute_and_instances(context)
File
"/home/titan/johnh/dev/lib/python2.4/site-packages/SQLAlchemy-0.5.0rc3dev_r5205-py2.4.egg/sqlalchemy/orm/query.py",
line 1085, in _execute_and_instances
result = self.session.execute(querycontext.statement,
params=self._params, mapper=self._mapper_zero_or_none(),
_state=self._refresh_state)
File
"/home/titan/johnh/dev/lib/python2.4/site-packages/SQLAlchemy-0.5.0rc3dev_r5205-py2.4.egg/sqlalchemy/orm/session.py",
line 749, in execute
return self.__connection(engine, close_with_result=True).execute(
File
"/home/titan/johnh/dev/lib/python2.4/site-packages/SQLAlchemy-0.5.0rc3dev_r5205-py2.4.egg/sqlalchemy/engine/base.py",
line 826, in execute
return Connection.executors[c](self, object, multiparams, params)
File
"/home/titan/johnh/dev/lib/python2.4/site-packages/SQLAlchemy-0.5.0rc3dev_r5205-py2.4.egg/sqlalchemy/engine/base.py",
line 877, in execute_clauseelement
return self._execute_compiled(elem.compile(dialect=self.dialect,
column_keys=keys, inline=len(params) > 1), distilled_params=params)
File
"/home/titan/johnh/dev/lib/python2.4/site-packages/SQLAlchemy-0.5.0rc3dev_r5205-py2.4.egg/sqlalchemy/engine/base.py",
line 889, in _execute_compiled
self.__execute_raw(context)
File
"/home/titan/johnh/dev/lib/python2.4/site-packages/SQLAlchemy-0.5.0rc3dev_r5205-py2.4.egg/sqlalchemy/engine/base.py",
line 898, in __execute_raw
self._cursor_execute(context.cursor, context.statement,
context.parameters[0], context=context)
File
"/home/titan/johnh/dev/lib/python2.4/site-packages/SQLAlchemy-0.5.0rc3dev_r5205-py2.4.egg/sqlalchemy/engine/base.py",
line 942, in _cursor_execute
self._handle_dbapi_exception(e, statement, parameters, cursor)
File
"/home/titan/johnh/dev/lib/python2.4/site-packages/SQLAlchemy-0.5.0rc3dev_r5205-py2.4.egg/sqlalchemy/engine/base.py",
line 924, in _handle_dbapi_exception
raise exc.DBAPIError.instance(statement, parameters, e,
connection_invalidated=is_disconnect)
ProgrammingError: (ProgrammingError) (1111, 'Invalid use of group
function') u'SELECT snapshot.symbol AS snapshot_symbol,
snapshot.strategy AS snapshot_strategy, snapshot.longshort AS
snapshot_longshort, snapshot.datetime AS snapshot_datetime,
snapshot.date AS snapshot_date, snapshot.year AS snapshot_year,
snapshot.month AS snapshot_month, snapshot.qty AS snapshot_qty,
snapshot.totalqty AS snapshot_totalqty, snapshot.price AS
snapshot_price, snapshot.possize AS snapshot_possize, snapshot.pnl AS
snapshot_pnl, snapshot.realized AS snapshot_realized,
snapshot.pnl_hedged AS snapshot_pnl_hedged, snapshot.is_stop AS
snapshot_is_stop, snapshot.stop_flag AS snapshot_stop_flag \nFROM
snapshot \nWHERE snapshot.totalqty = max(snapshot.totalqty)' []
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