2019 03 21 表單查詢

今日份python  表單查詢

有乙個叫orm模式的，會顯示sql底層**

當我們用python去查詢是，再用showsql就可以看到剛才查詢到的底層sql語句

在pycharm有個pythonconsole

顯示orm底層生成sql

def showsql():

from django.db import connection
queries = connection.queries
print queries[-1]['sql']
​

#所有的繼承自models.model的類 都會有乙個叫objects（管理器）

* 查詢乙個 （有且只能有乙個）（少於乙個或者多餘乙個都報錯）

* 返回值movie物件

movie.objects.get(mid=147)

select `movie`.`mid`, `movie`.`mname`, `movie`.`mdesc`, `movie`.`mimg`, `movie`.`mlink` from `movie` where `movie`.`mid` = 147

* 獲得第乙個

movie.objects.first()

select `movie`.`mid`, `movie`.`mname`, `movie`.`mdesc`, `movie`.`mimg`, `movie`.`mlink` from `movie` order by `movie`.`mid` asc limit 1

* 獲得最後乙個

movie.objects.last()

select `movie`.`mid`, `movie`.`mname`, `movie`.`mdesc`, `movie`.`mimg`, `movie`.`mlink` from `movie` order by `movie`.`mid` desc limit 1

* 獲得記錄的總數

movie.objects.count()

select count(*) as `__count` from `movie`

查詢多個物件

* 獲得所有的記錄

​movie.objects.all()
# 在diango的1.11.6中預設只是獲得21個，
# 懶載入
select `movie`.`mid`, `movie`.`mname`, `movie`.`mdesc`, `movie`.`mimg`, `movie`.`mlink` from `movie` limit 21
* 切片 （不支援負數索引）
movie.objects.all()[20:40]
# 底層直接使用了limit字句，可以自動的分頁
# django的orm效能非常強大，能節省很多任務作
select `movie`.`mid`, `movie`.`mname`, `movie`.`mdesc`, `movie`.`mimg`, `movie`.`mlink` from `movie` limit 20 offset 20
* 過濾
# 集和（游標，結果集，查詢集）
movie.objects.filter(mname='麻辣學院')
​select `movie`.`mid`, `movie`.`mname`, `movie`.`mdesc`, `movie`.`mimg`, `movie`.`mlink` from `movie` where `movie`.`mname` = '麻辣學院' limit 21
* 模糊查詢 
* like
* %(多個字元) _(乙個字元)
* select * from movie where mname like '%愛情_'
* 查詢愛情結尾的
​select * from movie where mname like '%愛情'
​movie.objects.filter(mname__endswith='愛情')
​select `movie`.`mid`, `movie`.`mname`, `movie`.`mdesc`, `movie`.`mimg`, `movie`.`mlink` from `movie` where `movie`.`mname` like binary '%愛情' limit 21
* 查詢愛情開頭的
​select * from movie where mname like '愛情%'
movie.objects.filter(mname__startswith='愛情')
select `movie`.`mid`, `movie`.`mname`, `movie`.`mdesc`, `movie`.`mimg`, `movie`.`mlink` from `movie` where `movie`.`mname` like binary '愛情%' limit 21
* 包含愛情的
​select * from movie where mname like '%愛情%'
​movie.objects.filter(mname__contains='愛情')​​
select `movie`.`mid`, `movie`.`mname`, `movie`.`mdesc`, `movie`.`mimg`, `movie`.`mlink` from `movie` where `movie`.`mname` like binary '%愛情%' limit 21
* 完全相等
​movie.objects.filter(mname__exact='麻辣學院')
movie.objects.filter(mname='麻辣學院')
select `movie`.`mid`, `movie`.`mname`, `movie`.`mdesc`, `movie`.`mimg`, `movie`.`mlink` from `movie` where `movie`.`mname` = '麻辣學院' limit 21
* 忽略大小寫
​movie.objects.filter(mname__istartswith='h')
​* 查詢某個字段是否為null
​movie.objects.filter(mname__isnull=true)​​
* 多條件查詢
​movie.objects.filter(mname__contains='愛情',mid=147)
and​
select `movie`.`mid`, `movie`.`mname`, `movie`.`mdesc`, `movie`.`mimg`, `movie`.`mlink` from `movie` where (`movie`.`mname` like binary '%愛情%' and `movie`.`mid` = 147) limit 21
​movie.objects.filter(mname__contains='愛情').filter(mid=147)
​* 部分查詢
​movie.objects.values('mname','mid').filter(mname__contains='愛情')
* 排除一部分
​movie.objects.filter(mname__contains='愛情').exclude(mname__startswith='愛情')
​select `movie`.`mid`, `movie`.`mname`, `movie`.`mdesc`, `movie`.`mimg`, `movie`.`mlink` from `movie` where (`movie`.`mname` like binary '%愛情%' and not (`movie`.`mname` like binary '愛情%')) limit 21
​* 排序
​movie.objects.order_by('mid')
select `movie`.`mid`, `movie`.`mname`, `movie`.`mdesc`, `movie`.`mimg`, `movie`.`mlink` from `movie` order by `movie`.`mid` asc limit 21​​
movie.objects.order_by('-mid')
​select `movie`.`mid`, `movie`.`mname`, `movie`.`mdesc`, `movie`.`mimg`, `movie`.`mlink` from `movie` order by `movie`.`mid` desc limit 21​​

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