Python peewee:如何基于另一个表中跨行的值筛选表中的数据
考虑以下支持peewee的python代码,如何基于另一个表中跨行的值筛选表中的数据 e、 g。 如果我想在note表中获得一个note,该表包含Python peewee:如何基于另一个表中跨行的值筛选表中的数据,python,sql,peewee,Python,Sql,Peewee,考虑以下支持peewee的python代码,如何基于另一个表中跨行的值筛选表中的数据 e、 g。 如果我想在note表中获得一个note,该表包含java,lambda,generics标签,位于customtags #!/usr/bin/env python3 import peewee import datetime db = peewee.SqliteDatabase('test.db') class Note(peewee.Model): id = peewee.AutoF
java
,lambda
,generics
标签,位于customtags
#!/usr/bin/env python3
import peewee
import datetime
db = peewee.SqliteDatabase('test.db')
class Note(peewee.Model):
id = peewee.AutoField()
name = peewee.CharField()
text = peewee.CharField()
created = peewee.DateField(default=datetime.date.today)
class Meta:
database = db
db_table = 'notes'
class CustomTag(peewee.Model):
id = peewee.AutoField()
note = peewee.ForeignKeyField(Note, backref='notes')
tag = peewee.CharField()
class Meta:
database = db
db_table = 'customtags'
indexes = ((("note_id", "tag"), True),)
Note.drop_table()
CustomTag.drop_table()
Note.create_table()
CustomTag.create_table()
note1 = Note.create(name="note1",text='Java 8 lambda with generics')
note1.save()
CustomTag.insert(note=note1, tag='java').on_conflict_ignore(True)
CustomTag.insert(note=note1, tag='lambda').on_conflict_ignore(True)
CustomTag.insert(note=note1, tag='generics').on_conflict_ignore(True)
note2 = Note.create(name="note2",text='Core Java concepts',
created=datetime.date(2018, 10, 20))
note2.save()
CustomTag.insert(note=note2, tag='java').on_conflict_ignore(True)
note3 = Note.create(name="note3",text='Java collection framework',
created=datetime.date(2018, 10, 22))
note3.save()
CustomTag.insert(note=note3, tag='java').on_conflict_ignore(True)
note4 = Note.create(name="note4",text='Java NIO packageJava nio package')
note4.save()
CustomTag.insert(note=note4, tag='java').on_conflict_ignore(True)
notes = Note.select().join(CustomTag, peewee.JOIN.LEFT_OUTER,on=(Note.id == CustomTag.note_id)).order_by(Note.name)
for note in notes:
print('{} with text {} on {}'.format(note.name, note.text, note.created))
我真的不知道如何修改我的代码来获取上面提到的数据,我知道问题出在下面的代码中
notes = Note.select().join(CustomTag, peewee.JOIN.LEFT_OUTER,on=(Note.id == CustomTag.note_id)).order_by(Note.name)
e、 如果我想在note表中得到一个note,在customtags中包含所有java、lambda、generics标记
insert语句中似乎缺少execute()
。它应该在每一行中更正
CustomTag.insert(note=note1, tag='java').on_conflict_ignore(True).execute()
我在这里加入了coleifer答案的改进版本,结果还包括标签列表
from peewee import fn
filter_tags = ['java', 'lambda', 'generics']
notes = (Note
.select(Note, fn.GROUP_CONCAT(CustomTag.tag,',').alias('tags'))
.join(CustomTag)
.where(CustomTag.tag.in_(filter_tags))
.group_by(Note)
.having(fn.COUNT(CustomTag.id) >= len(filter_tags)))
for note in notes:
print(f'name : {note.name} text: {note.text} tags: {note.tags} created : {note.created}')
from peewee import fn
filter_tags = ['java', 'lambda', 'generics']
notes = (Note
.select(Note, fn.GROUP_CONCAT(CustomTag.tag,',').alias('tags'))
.join(CustomTag)
.where(CustomTag.tag.in_(filter_tags))
.group_by(Note)
.having(fn.COUNT(CustomTag.id) >= len(filter_tags)))
for note in notes:
print(f'name : {note.name} text: {note.text} tags: {note.tags} created : {note.created}')