[Sqlalchemy-tickets] Issue #3120: sql.true() does not work for IBM DB2 (zzzeek/sqlalchemy)

[xtdxhw <iss...@bi...>]

New issue 3120: sql.true() does not work for IBM DB2
https://bitbucket.org/zzzeek/sqlalchemy/issue/3120/sqltrue-does-not-work-for-ibm-db2

xtdxhw:

When using sql.true() in query filter to query data in db2. It parse the sql.true() to 'true', which is a string. However, if changed sql.true() to 'True', it works well.

E.g. the following code works well.

```
#!python

class TT(Base):
    __tablename__ = 'tt'

    id = Column(Integer, primary_key = True)
    btest = Column('btest', Boolean, default = True)

db2 = sqlalchemy.create_engine('ibm_db_sa://neutron:neutron@localhost:50000/ntrnovs?charset=utf8')
session = sessionmaker( autocommit = False, autoflush = False, bind = db2)()
print session.query(TT).filter(TT.btest==True).all()[0].btest
```
However, if I changed the 'True' to 'sql.true()', it raise the following errors.

```
#!python
[root@rhel62 ~]# python db2_select.py 
Traceback (most recent call last):
  File "db2_select.py", line 18, in <module>
    print session.query(TT).filter(TT.btest==sql.true()).all()[0].btest
  File "/usr/lib64/python2.6/site-packages/sqlalchemy/orm/query.py", line 2115, in all
    return list(self)
  File "/usr/lib64/python2.6/site-packages/sqlalchemy/orm/query.py", line 2227, in __iter__
    return self._execute_and_instances(context)
  File "/usr/lib64/python2.6/site-packages/sqlalchemy/orm/query.py", line 2242, in _execute_and_instances
    result = conn.execute(querycontext.statement, self._params)
  File "/usr/lib64/python2.6/site-packages/sqlalchemy/engine/base.py", line 1449, in execute
    params)
  File "/usr/lib64/python2.6/site-packages/sqlalchemy/engine/base.py", line 1584, in _execute_clauseelement
    compiled_sql, distilled_params
  File "/usr/lib64/python2.6/site-packages/sqlalchemy/engine/base.py", line 1698, in _execute_context
    context)
  File "/usr/lib64/python2.6/site-packages/sqlalchemy/engine/base.py", line 1691, in _execute_context
    context)
  File "/usr/lib/python2.6/site-packages/ibm_db_sa/ibm_db.py", line 104, in do_execute
    cursor.execute(statement, parameters)
  File "/usr/lib64/python2.6/site-packages/ibm_db_dbi.py", line 1334, in execute
    self._set_cursor_helper()
  File "/usr/lib64/python2.6/site-packages/ibm_db_dbi.py", line 1217, in _set_cursor_helper
    raise self.messages[len(self.messages) - 1]
sqlalchemy.exc.ProgrammingError: (ProgrammingError) ibm_db_dbi::ProgrammingError: SQLNumResultCols failed: [IBM][CLI Driver][DB2/LINUXX8664] SQL0401N  The data types of the operands for the operation "=" are not compatible or comparable.  SQLSTATE=42818 SQLCODE=-401 'SELECT tt.id AS tt_id, tt.btest AS tt_btest \nFROM tt \nWHERE tt.btest = true' ()
```
[root@rhel62 ~]# rpm -qa | grep sqlalchemy
python-sqlalchemy-0.7.9-1