SQLAlchemy ORM高级查询之过滤，排序

order_by,filter的语法。

用久了才会熟悉。

Session = sessionmaker(bind=engine)
session = Session()

print(session.query(Cookie.cookie_name, Cookie.quantity).first())

for cookie in session.query(Cookie).order_by(desc(Cookie.quantity)):
    print('{:3} - {}'.format(cookie.quantity, cookie.cookie_name))

# query = session.query(Cookie).order_by(Cookie.quantity)[:2]
query = session.query(Cookie).order_by(Cookie.quantity).limit(4)
print([result.cookie_name for result in query])

inv_count = session.query(func.sum(Cookie.quantity)).scalar()
print(inv_count)

rec_count = session.query(func.count(Cookie.cookie_name)).first()
print(rec_count)

rec_count = session.query(func.count(Cookie.cookie_name).label('inventory_count')).first()
print(rec_count.keys())
print(rec_count.inventory_count)

record = session.query(Cookie).filter(Cookie.cookie_name == 'chocolate chip').first()
print record

record = session.query(Cookie).filter_by(cookie_name='chocolate chip').first()
print(record)

query = session.query(Cookie).filter(Cookie.cookie_name.like('%chocolate%'))
for record in query:
    print(record.cookie_name)

results = session.query(Cookie.cookie_name, 'SKU-' + Cookie.cookie_sku).all()
for row in results:
    print(row)

query = session.query(Cookie.cookie_name, cast((Cookie.quantity * Cookie.unit_cost),
                                               Numeric(12, 2)).label('inv_cost'))
for result in query:
    print('{} - {}'.format(result.cookie_name, result.inv_cost))

query = session.query(Cookie).filter(
    Cookie.quantity > 23,
    Cookie.unit_cost < 0.40
    )
for result in query:
    print(result.cookie_name)

query = session.query(Cookie).filter(
    or_(
        Cookie.quantity.between(10, 50),
        Cookie.cookie_name.contains('chip')
        )
    )
for result in query:
    print(result.cookie_name)

输出：

('chocolate chip', 12)
100 - oatmeal raisin
 24 - peanut butter
 12 - chocolate chip
 12 - chocolate chip
 12 - chocolate chip
 12 - chocolate chip
  1 - dark chocolate chip
  1 - molasses
  1 - dark chocolate chip
  1 - molasses
['dark chocolate chip', 'molasses', 'dark chocolate chip', 'molasses']
176
(10,)
['inventory_count']
10
Cookie(cookie_name='chocolate chip', cookie_recipe_url='http://www.baidu.com/', cookie_sku='CC01', quantity=12, unit_cost=0.50)
Cookie(cookie_name='chocolate chip', cookie_recipe_url='http://www.baidu.com/', cookie_sku='CC01', quantity=12, unit_cost=0.50)
chocolate chip
chocolate chip
chocolate chip
dark chocolate chip
chocolate chip
dark chocolate chip
('chocolate chip', 'SKU-CC01')
('chocolate chip', 'SKU-CC01')
('chocolate chip', 'SKU-CC01')
('dark chocolate chip', 'SKU-CC02')
('molasses', 'SKU-MOL01')
('chocolate chip', 'SKU-CC01')
('dark chocolate chip', 'SKU-CC02')
('molasses', 'SKU-MOL01')
('peanut butter', 'SKU-PB01')
('oatmeal raisin', 'SKU-EWW01')
chocolate chip - 6.00
chocolate chip - 6.00
chocolate chip - 6.00
dark chocolate chip - 0.75
molasses - 0.80
chocolate chip - 6.00
dark chocolate chip - 0.75
molasses - 0.80
peanut butter - 6.00
oatmeal raisin - 100.00
peanut butter
chocolate chip
chocolate chip
chocolate chip
dark chocolate chip
chocolate chip
dark chocolate chip
peanut butter