Hello,
I'm use SQLAlchemy for work with existing Oracle DB(Python 3.5.4,
SQLAlchemy 1.2.11, cx_Oracle 6.1, Oacle Client 11g1).
I reflecting tables and views(including materialized views) for quering
data.
Example:
Tere is MV exists in DB
create materialized view test_mv_table
refresh force on demand
as
select
nvl(exp(sum(ln(abs(case when 0.1 <> 0 then 0.1 end)))) * decode(mod(sum(
decode(sign(0.1), 0, 0, 1,0,1)), 2), 0, 1,-1),0) * nvl(sum(case when sign(
0.1) = 0 then 0 end), 1) as number_column_eval,
0.1 as number_column_constant
from dual
Column number_column_constant defined explicitly as 0.1 and
number_column_eval is result of evaluation equal the same 0.1
sqlplus qury result is:
SQL> select * from test_mv_table;
> NUMBER_COLUMN_EVAL NUMBER_COLUMN_CONSTANT
> ------------------ ----------------------
> .1 .1
Both values representation is '0.1'.
Now I query data in code:
from sqlalchemy import create_engine, MetaData
from sqlalchemy.orm import sessionmaker
# Reflect table
eng = create_engine('CONNECTION_STRING')
md = MetaData()
md.reflect(bind=eng, only=['test_mv_table', ])
test_mv_table = md.tables['test_mv_table']
# Set asdecimal=True
test_mv_table.columns.number_column_constant.type.asdecimal=True
test_mv_table.columns.number_column_eval.type.asdecimal=True
# Get data
session = sessionmaker(bind=eng)()
mv_res = session.query(test_mv_table.c.number_column_constant, test_mv_table
.c.number_column_eval).all()
session.close()
# Print result
print(mv_res)
So I get result:
[(Decimal('0.1'), Decimal('0.1000000000000000000000000000000000000003'))]
but expect that values will be equal(as it is when i query data by sblplus).
I will be grateful if somebody explain to me why the value of
number_column_eval was not quered as 0.1 and how I can get it as Decimal
represented as 0.1.
--
SQLAlchemy -
The Python SQL Toolkit and Object Relational Mapper
http://www.sqlalchemy.org/
To post example code, please provide an MCVE: Minimal, Complete, and Verifiable
Example. See http://stackoverflow.com/help/mcve for a full description.
---
You received this message because you are subscribed to the Google Groups
"sqlalchemy" group.
To unsubscribe from this group and stop receiving emails from it, send an email
to sqlalchemy+unsubscr...@googlegroups.com.
To post to this group, send email to sqlalchemy@googlegroups.com.
Visit this group at https://groups.google.com/group/sqlalchemy.
For more options, visit https://groups.google.com/d/optout.
