Adding table records
Many:
# Mode. 1:
publish_obj = Publish.objects.get (= ID. 1)
Book.objects.create (name = '2 Books', =. Price 200 is, publishs = publish_obj)
# mode 2:
Book.objects.create (name = '3 Books', price = 300, publish_id = 1)
Many to many:
book_obj = Book.objects.filter(name='2号图书').first()
author1_obj = Author.objects.get(name='1号作者')
author2_obj = Author.objects.get(name='2号作者')
book_obj.authors.add(author1_obj,author2_obj)
Lookup table records
- Mode 1: Object-based
- Option 2: Based on double underscore
One:
Reverse query #
# mode. 1:
author_detail_list = AuthorDetail.objects.filter (addr = 'address')
for obj in author_detail_list:
Print (obj.author.name)
# mode 2:
AuthorDetail.objects.filter (author__name =' 2 author ') .values ( "addr")
# forward queries
# mode 1:
Author.objects.filter (name ='. author No. 1 ') .first () authordetail.addr
# mode 2:
Author.objects.filter ( name = '1 author') .values ( "authordetail__addr")
Many:
# Forward queries (by field) # 1 way: # Query No. 1 book publisher name Book.objects.filter (the above mentioned id = 1) .first () publishs.name. # 2 ways: # Query No. 1 book publishing agency name and address Book.objects.filter (the above mentioned id = 1) .values_list ( "publishs__name", "publishs__addr") # reverse lookup (by table name: table name _set) # 1 way: # 1 query Publishing All books Publish.objects.get (name = 'Press 1') .book_set.all () # 2 ways: # query No. 1 book publisher's name and address Publish.objects.filter (book__id = 1) .values_list ( "name", "addr ")
Many to many:
With many
Aggregate query:
aggregate(*args, **kwargs)
Returns a dictionary, a polymerization key identifier value, can be specified freely, may not specify
example：
# Do not specify a key Book.objects.all (). Aggregate (Avg ( ". Price")) # specified key Book.objects.all (). Aggregate (price_avg = Avg ( "price"))
Grouping queries:
example：
Single table #
# Book.objects.values RET = ( ". Price"). Annotate (the Count ( "ID"))
# polyepitopic
ret = AuthorDetail.objects.values ( "addr") . Annotate (c = Count ( "author ")). values (" addr "," C ")
# polyepitopic identical to join association table packet, then the query packet
F query:
Comparison is made between the field values, between the support and the objects constant, between the object and the object and the addition, subtraction modulo operation.
example：
F django.db.models Import from # inquiry number is greater than the number of browsers read the Book.objects.filter (readNum__lt = F ( 'scanNum '))
Q query:
Support and, or, not, and other complex queries, parameters can be used with keywords, but the object to be placed in front of Q
example：
from django.db.models import Q Book.objects.filter(Q(authors__name="2号作者")|Q(authors__name="1号作者"))