Django_数据库增删改查——查

Posted 2021-03-03 wangdianchao

查：

 

 

filter 支持很多的过滤条件，我们来看下：

 

 

contains

包含，相当于sql的like条件

1	Entry.objects.get(headline__contains=‘Lennon‘)

SQL equivalent:

1	SELECT ... WHERE headline LIKE ‘%Lennon%‘;

Note this will match the headline ‘Lennon honored today‘ but not ‘lennon honored today‘.

icontains  大小写不敏感　　

　　

in

In a given iterable; often a list, tuple, or queryset.

1	Entry.objects.filter(id__in=[1, 3, 4])

SQL equivalent:

1	SELECT ... WHERE id IN (1, 3, 4);

You can also use a queryset to dynamically evaluate the list of values instead of providing a list of literal values:

1 2	inner_qs = Blog.objects.filter(name__contains=‘Cheddar‘) entries = Entry.objects.filter(blog__in=inner_qs)

This queryset will be evaluated as subselect statement:

1	SELECT ... WHERE blog.id IN (SELECT id FROM ... WHERE NAME LIKE ‘%Cheddar%‘)

　　

gt

1	Entry.objects.filter(id__gt=4)

SQL equivalent:

1	SELECT ... WHERE id > 4;

gte
Greater than or equal to.

lt
Less than.

lte
Less than or equal to.

startswith
Case-sensitive starts-with.

1	Entry.objects.filter(headline__startswith=‘Lennon‘)

SQL equivalent:

1	SELECT ... WHERE headline LIKE ‘Lennon%‘;

SQLite doesn’t support case-sensitive LIKE statements; startswith acts like istartswith for SQLite　　

istartswith
Case-insensitive starts-with.

endswith
Case-sensitive ends-with.

iendswith
Case-insensitive ends-with

　　

range
区间过渡，可对数字、日期进行过滤

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import datetime start_date = datetime.date(2005, 1, 1) end_date = datetime.date(2005, 3, 31) Entry.objects.filter(pub_date__range=(start_date, end_date))

SQL equivalent:

1	SELECT ... WHERE pub_date BETWEEN ‘2005-01-01‘ and ‘2005-03-31‘;

Warning！

Filtering a DateTimeField with dates won’t include items on the last day, because the bounds are interpreted as “0am on the given date”. If pub_date was a DateTimeField, the above expression would be turned into this SQL:

SELECT ... WHERE pub_date BETWEEN ‘2005-01-01 00:00:00‘ and ‘2005-03-31 00:00:00‘;
Generally speaking, you can’t mix dates and datetimes.　

　　

date

For datetime fields, casts the value as date. Allows chaining additional field lookups. Takes a date value.　　

1 2	Entry.objects.filter(pub_date__date=datetime.date(2005, 1, 1)) Entry.objects.filter(pub_date__date__gt=datetime.date(2005, 1, 1))

year
For date and datetime fields, an exact year match. Allows chaining additional field lookups. Takes an integer year.

1 2	Entry.objects.filter(pub_date__year=2005) Entry.objects.filter(pub_date__year__gte=2005)

SQL equivalent:

1 2	SELECT ... WHERE pub_date BETWEEN ‘2005-01-01‘ AND ‘2005-12-31‘; SELECT ... WHERE pub_date >= ‘2005-01-01‘;

When USE_TZ is True, datetime fields are converted to the current time zone before filtering. 简单解决办法是把USE_TZ=False

month
For date and datetime fields, an exact month match. Allows chaining additional field lookups. Takes an integer 1 (January) through 12 (December).

1 2	Entry.objects.filter(pub_date__month=12) Entry.objects.filter(pub_date__month__gte=6)

When USE_TZ is True, datetime fields are converted to the current time zone before filtering. This requires time zone definitions in the database.

SQL equivalent:

1 2	SELECT ... WHERE EXTRACT(‘month‘ FROM pub_date) = ‘12‘; SELECT ... WHERE EXTRACT(‘month‘ FROM pub_date) >= ‘6‘;

day
For date and datetime fields, an exact day match. Allows chaining additional field lookups. Takes an integer day.

1 2	Entry.objects.filter(pub_date__day=3) Entry.objects.filter(pub_date__day__gte=3)

SQL equivalent:

1 2	SELECT ... WHERE EXTRACT(‘day‘ FROM pub_date) = ‘3‘; SELECT ... WHERE EXTRACT(‘day‘ FROM pub_date) >= ‘3‘;

　　

week

New in Django 1.11.

For date and datetime fields, return the week number (1-52 or 53) according to ISO-8601, i.e., weeks start on a Monday and the first week contains the year’s first Thursday.

Example:

1 2	Entry.objects.filter(pub_date__week=52) Entry.objects.filter(pub_date__week__gte=32, pub_date__week__lte=38)

week_day

For date and datetime fields, a ‘day of the week’ match. Allows chaining additional field lookups.

Takes an integer value representing the day of week from 1 (Sunday) to 7 (Saturday).

Example:

1 2	Entry.objects.filter(pub_date__week_day=2) Entry.objects.filter(pub_date__week_day__gte=2)

hour

For datetime and time fields, an exact hour match. Allows chaining additional field lookups. Takes an integer between 0 and 23.

Example:

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Event.objects.filter(timestamp__hour=23) Event.objects.filter(time__hour=5) Event.objects.filter(timestamp__hour__gte=12)

SQL equivalent:

1 2 3

SELECT ... WHERE EXTRACT(‘hour‘ FROM timestamp) = ‘23‘; SELECT ... WHERE EXTRACT(‘hour‘ FROM time) = ‘5‘; SELECT ... WHERE EXTRACT(‘hour‘ FROM timestamp) >= ‘12‘;同

同时，还支持mintue,second

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Event.objects.filter(time__minute=46)     Event.objects.filter(timestamp__second=31)