python - Python 查询 - Web 应用程序等

Question

def get_songs(requested_username):
   songs = db.GqlQuery("SELECT * FROM Song ORDER BY created DESC")

Song db.Model 实体有一个用户名属性。

如果一首歌的用户名属性等于请求的用户名，我如何从一个特定的用户名中找到所有歌曲？

Answer 1

你可以通过两种方式做到这一点：

GQL

def get_songs(requested_username):
    songs = db.GqlQuery('SELECT * FROM Song WHERE username=:1 ORDER BY created DESC', requested_username)
    return songs

查询实例：

def get_songs(requested_username):
    songs = Song.all()
    songs.filter('username =', requested_username).order('-created')
    return songs

在这两种情况下，songs都将包含查询的结果，您可以对其进行迭代并根据需要访问其中的对象。

songs = get_songs(requested_username)
for song in songs:
  # Do stuff here...

Answer 2

就像是

SELECT * FROM Song where username="Batman" ORDER BY created DESC

在这种情况下你可能不想使用蝙蝠侠

Answer 3

建议您查看文档-> https://developers.google.com/appengine/docs/python/datastore/queries#Filters

但要回答你的问题，是这样的：

def get_songs(requested_username, limit=10):
   query = db.GqlQuery("SELECT * FROM Song WHERE username = :1 ORDER BY created DESC", requested_username)
   songs = query.fetch(limit)
   return songs