我试图重现SQLAlchemy的文档页面上找到this查询递归查询CTE(瓶/ SQLAlchemy的)。设立在models.py
的Part
下课后,这是我有:如何解决“近‘与’:语法错误”
from app import app, db, models
from models import *
@app.route('/')
def test():
included_parts = db.session.query(
Part.sub_part,
Part.part,
Part.quantity).\
filter(Part.part=="our part").\
cte(name="included_parts", recursive=True)
incl_alias = db.aliased(included_parts, name="pr")
parts_alias = db.aliased(Part, name="p")
included_parts = included_parts.union_all(
db.session.query(
parts_alias.sub_part,
parts_alias.part,
parts_alias.quantity).\
filter(parts_alias.part==incl_alias.c.sub_part)
)
q = db.session.query(
included_parts.c.sub_part,
db.func.sum(included_parts.c.quantity).
label('total_quantity')
).\
group_by(included_parts.c.sub_part).all()
return 'test complete'
但是,这给出了一个错误:
OperationalError: (sqlite3.OperationalError) near "WITH": syntax error [SQL: u'WITH RECURSIVE included_parts(sub_part, part, quantity) AS \n(SELECT parts.sub_part AS sub_part, parts.part AS part, parts.quantity AS quantity \nFROM parts \nWHERE parts.part = ? UNION ALL SELECT p.sub_part AS p_sub_part, p.part AS p_part, p.quantity AS p_quantity \nFROM parts AS p, included_parts AS pr \nWHERE p.part = pr.sub_part)\n SELECT included_parts.sub_part AS included_parts_sub_part, sum(included_parts.quantity) AS total_quantity \nFROM included_parts GROUP BY included_parts.sub_part'] [parameters: ('our part',)]
生成的查询(复制从错误信息粘贴)看起来是这样的:
WITH RECURSIVE included_parts(sub_part, part, quantity) AS \n(SELECT parts.sub_part AS sub_part, parts.part AS part, parts.quantity AS quantity \nFROM parts \nWHERE parts.part = ? UNION ALL SELECT p.sub_part AS p_sub_part, p.part AS p_part, p.quantity AS p_quantity \nFROM parts AS p, included_parts AS pr \nWHERE p.part = pr.sub_part)\n SELECT included_parts.sub_part AS included_parts_sub_part, sum(included_parts.quantity) AS total_quantity \nFROM included_parts GROUP BY included_parts.sub_part
格式化(在不同的地方换行的可读性):
WITH RECURSIVE included_parts(sub_part, part, quantity) AS (
SELECT parts.sub_part AS sub_part, parts.part AS part, parts.quantity AS quantity
FROM parts
WHERE parts.part = ?
UNION ALL
SELECT p.sub_part AS p_sub_part, p.part AS p_part, p.quantity AS p_quantity
FROM parts AS p, included_parts AS pr
WHERE p.part = pr.sub_part
)
SELECT included_parts.sub_part AS included_parts_sub_part, sum(included_parts.quantity) AS total_quantity
FROM included_parts
GROUP BY included_parts.sub_part
而且,作为比较,这里的SQLAlchemy的文档link纯PostgreSQL的查询:
WITH RECURSIVE included_parts(sub_part, part, quantity) AS (
SELECT sub_part, part, quantity FROM parts WHERE part = 'our_product'
UNION ALL
SELECT p.sub_part, p.part, p.quantity
FROM included_parts pr, parts p
WHERE p.part = pr.sub_part
)
SELECT sub_part, SUM(quantity) as total_quantity
FROM included_parts
GROUP BY sub_part
,我可以在Postgre查询之间看到的唯一差别(我认为应该工作)和我正在生成的一个是:
- 所有额外的 “AS” 语句(
SELECT parts.sub_part AS sub_part
VSSELECT sub_part
) - 不同的格式(生成的查询^ h换行符怪异点 - 例如,
UNION ALL
和SELECT
)
但是,据我可以告诉之间没有断行,这些都不应该导致语法错误... 我也试过执行Postgre查询作为原始SQL(虽然SQLAlchemy使用sqlite3,显然,但仍然):
query = db.engine.execute(\
'''WITH RECURSIVE included_parts(sub_part, part, quantity) AS (
SELECT sub_part, part, quantity FROM parts WHERE part = 'our_product'
UNION ALL
SELECT p.sub_part, p.part, p.quantity
FROM included_parts pr, parts p
WHERE p.part = pr.sub_part
)
SELECT sub_part, SUM(quantity) as total_quantity
FROM included_parts
GROUP BY sub_part''').all()
但我仍然收到语法错误。
OperationalError: (sqlite3.OperationalError) near "WITH": syntax error [SQL: "WITH RECURSIVE included_parts(sub_part, part, quantity) AS (\nSELECT sub_part, part, quantity FROM parts WHERE part = 'our_product'\nUNION ALL\nSELECT p.sub_part, p.part, p.quantity\nFROM included_parts pr, parts p\nWHERE p.part = pr.sub_part\n)\nSELECT sub_part, SUM(quantity) as total_quantity\nFROM included_parts\nGROUP BY sub_part"]
我也尝试重新格式化生成的查询并将其作为原始SQL执行,结果类似。
最后,我试图写的SQLite查询和执行它:
WITH RECURSIVE included_parts(sub_part, part, quantity) AS (
SELECT sub_part, part, quantity FROM parts WHERE part="our_product"
UNION ALL
SELECT parts.sub_part, parts.part, parts.quantity FROM parts, included_parts WHERE parts.part=included_parts.sub_part
)
SELECT sub_part, SUM(quantity) AS total_quantity
FROM included_parts
GROUP BY sub_part
这也抛出一个语法错误。
在这一点上,我真的不知道该怎么办...好像连WITH
查询有正确的语法仍然会抛出一个错误。我知道,递归CTE查询在SQLAlchemy的支持,根据文档,并根据此(_http://stackoverflow.com/a/24780445)回答这里。老实说,我不知道为什么所有这些疑问都被认为有错误的语法。我的python代码与文档中的示例几乎完全相同。
我需要安装的东西WITH RECURSIVE
在SQLAlchemy的工作?我的语法实际上错了吗?在这里失去了很多,任何帮助表示赞赏。我希望我可以说我已经取得了一些进展,但我几乎不知道该怎么做,这是PostgreSQL vs SQLite的问题吗?有没有人有我想要做的,我可以看看的工作示例?)
这工作,谢谢!我不得不改变pysqlite的配置文件(https://github.com/ghaering/pysqlite/issues/60),但是一旦实际安装完成,它就可以完美运行。 –