2
2子句
我有以下pyDAL表:创建HAVING COUNT(列)>在pyDAL
market = db.define_table(
'market',
Field('name'),
Field('ask', type='double'),
Field('timestamp', type='datetime', default=datetime.now)
)
我想用表达式语言来执行以下SQL:
SELECT * FROM market
GROUP BY name
ORDER BY timestamp DESCENDING
HAVING COUNT(name) > 1
我知道该怎么做了ORDER BY
和GROUP BY
:
db().select(
db.market.ALL,
orderby=~db.market.timestamp,
groupby=db.market.name
)
,但我不知道该怎么做即使在阅读the section in the web2py book on the HAVING
clause之后,也可以在一个条款中计数。