Thank you for your information..... On Monday, September 2, 2013 2:33:21 AM UTC+4:30, Simon King wrote: > > On 1 Sep 2013, at 18:27, Mohsen Pahlevanzadeh > <m.pahle...@gmail.com<javascript:>> > wrote: > > > Dear all, > > > > Before apply code or writing code from a documentation, At first i test > it into test.py, > > Now ,I read the following doc: > > conjuctions in sqlalchemy > > > > I supposed users a class such as tables class: > > ////////////////////// > > class users(declarative_base(bind=engine)): > > > > __tablename__ = 'users'; # > > id = Column(Integer,primary_key = True) > > name = Column(String) > > name_type = Column(Integer) > > addresses = Column(String) > > telephones = Column(String) > > emails = Column(String) > > ////////////////// > > > > But i didn't understand c variable. Object or otehr variable such : > > /////////////// > > addresses.c.email_address or users.c.id == addresses.c.user_id > > ///////////////// > > > > > > If possible explain c object. > > The SQLAlchemy library has 2 main parts. The lower layer is known as the > Core API, and works with Table objects: > > > http://docs.sqlalchemy.org/en/rel_0_8/core/tutorial.html#define-and-create-tables > > > Table objects have a "columns" attribute (which is usually abbreviated to > "c") which gives you access to the columns of the table: > > > http://docs.sqlalchemy.org/en/rel_0_8/core/metadata.html#accessing-tables-and-columns > > > Table objects also have lots of other methods, such as ones for creating > SELECT, UPDATE and DELETE statements, and so on. > > The ORM is built on top of the Core API. When you create classes that > inherit from a declarative_base class, you are creating a "mapped class". > Mapped classes don't have a "c" attribute because you can access the > columns directly from the class itself. To perform SELECT, UPDATE and > DELETE statements on these classes, you use the Session and Query objects. > If you ever need the underlying Table object, you can get it from your > mapped class via the "__table__" attribute, but most of the time you don't > need it. > > Hope that helps, > > Simon
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