peewee模块基本使用-ORM

Method  Meaning
.in_(value) IN lookup (identical to <<).
.not_in(value)  NOT IN lookup.
.is_null(is_null)   IS NULL or IS NOT NULL. Accepts boolean param.
.contains(substr)   Wild-card search for substring.
.startswith(prefix) Search for values beginning with prefix.
.endswith(suffix)   Search for values ending with suffix.
.between(low, high) Search for values between low and high.
.regexp(exp)    Regular expression match (case-sensitive).
.iregexp(exp)   Regular expression match (case-insensitive).
.bin_and(value) Binary AND.
.bin_or(value)  Binary OR.
.concat(other)  Concatenate two strings or objects using ||.
.distinct() Mark column for DISTINCT selection.
.collate(collation) Specify column with the given collation.
.cast(type) Cast the value of the column to the given type.

in_(): IN
not_in(): NOT IN
regexp(): REGEXP
is_null(True/False): IS NULL or IS NOT NULL
contains(s): LIKE %s%
startswith(s): LIKE s%
endswith(s): LIKE %s
between(low, high): BETWEEN low AND high
concat(): ||

SELECT * FROM user WHERE username not like "%admin%"
# ~(User.username.contains('admin'))
SELECT * FROM user WHERE LENGTH(username)>45
# fn.length(User.username) > 45

query = (User
         .select(User.username, fn.COUNT(Tweet.id).alias('ct'))
         .join(Tweet, JOIN.LEFT_OUTER, on=(User.id == Tweet.user_id))
         .group_by(User.username)
         .order_by(fn.COUNT(Tweet.id).desc()))

# —*— coding: utf-8 —*—
from peewee import *
import datetime
from chinesename import chinesename
# py2解决编码问题
import sys
reload(sys)
sys.setdefaultencoding("utf-8")
# 设置数据库
db = SqliteDatabase("demo.db")
class BaseModel(Model):
    class Meta:
        database = db
# 定义数据表
class User(BaseModel):
    name = CharField(unique=True)
    def __str__(self):
        return "[user] id: %d  name: %s"%(self.id, self.name)
class Tweet(BaseModel):
    user = ForeignKeyField(User, related_name ="tweets")
    message = TextField()
    created_date = DateTimeField(default=datetime.datetime.now)
    is_published = BooleanField(default=True)
    def __str__(self):
        return "[tweet] id: %d  name: %s" % (self.id, self.user.name)
# 创建数据表
db.connect()
db.create_tables([User, Tweet], safe=True)
db.close()
# 添加数据
def add_data():
    cn = chinesename.ChineseName()
    for i in range(100):
        user = User(name=cn.getName())
        user.save()
        User.create(name=cn.getName())
        Tweet.create(user=user, message="hello world")
# add_data()
print datetime.datetime.now()
print datetime.date.today()
# 查询
ret = User.get(User.name=="沈从")
if ret: print ret
usernames = ["马酿", "沈从"]
users = User.select().where(User.name.in_(usernames))
for user in users:
    print user
tweets = Tweet.select().where(Tweet.user.in_(users))
for tweet in tweets:
    print tweet
tweets = Tweet.select().join(User).where(User.name.in_(usernames))
for tweet in tweets:
    print tweet
count = (Tweet
         .select()
         .where(
            (Tweet.created_date >= datetime.date.today())&
            (Tweet.is_published == True))
         .count())
print count
# 分页 page 3 (users 41-60)
users = User.select().order_by(User.name).paginate(3, 20)
for user in users:
    print user
# 更新
query = User.update(name="西门吹雪").where(User.id==1)
query.execute()
# 删除
query = User.delete().where(User.id==2)
query.execute()