第五天
from django.db.models import Count
q = Blog.objects.annotate(Count('entry'))
q
Blog: Blog 1>, <Blog: Foo>]
q[0].name
Blog 1'
q[0].entry__count
3
q = Blog.objects.annotate(Avg('entry'))
q[0].entry__avg
2.0
dir(q1)
['DoesNotExist', 'MultipleObjectsReturned', '__class__', '__delattr__', '__dict_
_', '__doc__', '__eq__', '__getattribute__', '__hash__', '__init__', '__metaclas
s__', '__module__', '__ne__', '__new__', '__reduce__', '__reduce_ex__', '__repr_
_', '__setattr__', '__str__', '__unicode__', '__weakref__', '_base_manager', '_c
ollect_sub_objects', '_default_manager', '_deferred', '_get_FIELD_display', '_ge
t_next_or_previous_by_FIELD', '_get_next_or_previous_in_order', '_get_pk_val', '
_meta', '_set_pk_val', 'delete', 'entry__count', 'entry_set', 'id', 'name', 'obj
ects', 'pk', 'prepare_database_save', 'save', 'save_base', 'serializable_value',
'tagline']
q1.entry_set
<django.db.models.fields.related.RelatedManager object at 0x011F0430>
q1.entry_set.all()
[<Entry: Headline 1>, <Entry: 2>, <Entry: for the first>]
type(q1)
<class 'newtest.query.models.Blog'>
from django.db import connection
from django.db import connection as c
c.queries
c.queries = []
q1.entry_set.all()
[<Entry: 2>, <Entry: for the first>]
>>> c.queries
[{'time': '0.000', 'sql': u'SELECT "query_entry"."id", "query_entry"."blog_id",
"query_entry"."headline", "query_entry"."body_text", "query_entry"."pub_date", "
query_entry"."n_comments", "query_entry"."n_pingbacks", "query_entry"."rating" F
ROM "query_entry" WHERE "query_entry"."blog_id" = 1 LIMIT 21'}]
>>> q = Blog.objects.annotate(Count('entry'))
>>> c.queries
[{'time': '0.000', 'sql': u'SELECT "query_entry"."id", "query_entry"."blog_id",
"query_entry"."headline", "query_entry"."body_text", "query_entry"."pub_date", "
query_entry"."n_comments", "query_entry"."n_pingbacks", "query_entry"."rating" F
ROM "query_entry" WHERE "query_entry"."blog_id" = 1 LIMIT 21'}]
>>> q
[<Blog: Blog 1>, <Blog: Foo>]
>>> c.queries
[{'time': '0.000', 'sql': u'SELECT "query_entry"."id", "query_entry"."blog_id",
"query_entry"."headline", "query_entry"."body_text", "query_entry"."pub_date", "
query_entry"."n_comments", "query_entry"."n_pingbacks", "query_entry"."rating" F
ROM "query_entry" WHERE "query_entry"."blog_id" = 1 LIMIT 21'}, {'time': '0.000
', 'sql': u'SELECT "query_blog"."id", "query_blog"."name", "query_blog"."tagline
", COUNT("query_entry"."id") AS "entry__count" FROM "query_blog" LEFT OUTER JOIN
"query_entry" ON ("query_blog"."id" = "query_entry"."blog_id") GROUP BY "query_
blog"."id", "query_blog"."name", "query_blog"."tagline" LIMIT 21'}]
>>> q = Blog.objects.annotate(Avg('entry'))
>>> q
[<Blog: Blog 1>, <Blog: Foo>]
>>> q[0].entry__avg
2.5
>>> cc.queries
[{'time': '0.000', 'sql': u'SELECT "query_blog"."id", "query_blog"."name", "qu
y_blog"."tagline", AVG("query_entry"."id") AS "entry__avg" FROM "query_blog" L
T OUTER JOIN "query_entry" ON ("query_blog"."id" = "query_entry"."blog_id") GR
P BY "query_blog"."id", "query_blog"."name", "query_blog"."tagline" LIMIT 21'}
{'time': '0.000', 'sql': u'SELECT "query_blog"."id", "query_blog"."name", "que
_blog"."tagline", AVG("query_entry"."id") AS "entry__avg" FROM "query_blog" LE
OUTER JOIN "query_entry" ON ("query_blog"."id" = "query_entry"."blog_id") GRO
BY "query_blog"."id", "query_blog"."name", "query_blog"."tagline" LIMIT 1'}]
组长一席话，胜看半天书啊，要不是点拨一下，我还真不知道要如何看下去。
因为我，看不懂。（也不全是啦）
该死的英文，它解释的再详细，可是，思路上还是理不清的乱，你说，用英语解释的，我勉强知道意思，可也感觉不太对啊。。。我想死。。。