Sqlalchemy 将 WHERE 子句复制到 FROM [英] Sqlalchemy duplicated WHERE clause to FROM

问题描述

我向 psql 写了原始查询，它工作正常，但是当我在 sqlalchemy 中写这个时，我的 WHERE 子句复制到了 FROM 子句.

I wrote raw query to psql and it's work fine but when i wrote this in sqlalchemy my WHERE clause duplicated to FROM clause.

select id from T1 where arr && array(select l.id from T1 as l where l.box && box '((0,0),(50,50))');

在此查询中，我从 T1 中获取所有 id，其中整数数组与子查询的结果相交.

In this query i fetch all id from T1 where array with ints intersects with results from subquery.

class T1():
    arr = Column(ARRAY(Integer))
    ...

class T2():
    box = Column(Box)  # my geometry type
    ...

1 个版本:

layers_q = select([T2.id]).where(T2.box.op('&&')(box))  # try find all T2 intersects with box
chunks = select([T1.id]).where(T1.arr.overlap(layers_q))  # try find all T1.id where T1.arr overlap with result from first query 


SELECT T1.id 
FROM T1 
WHERE T1.arr && (SELECT T2.id 
FROM T2 
WHERE T2.box && %(box_1)s)

我有一个关于类型转换的 PG 错误.我明白了.

This i have a PG error about type cast. I understand it.

2 版本:

layers_q = select([T2.id]).where(T2.box.op('&&')(box))
chunks = select([T1.id]).where(T1.arr.overlap(func.array(layers_q)))

我添加了 func.array() 用于强制转换为数组但结果不正确:

I added func.array() for cast to array but result is not correct:

SELECT T1.id 
FROM T1, (SELECT T2.id AS id 
FROM T2 
WHERE T2.box && %(box_1)s) 
WHERE T1.arr && array((SELECT T2.id 
FROM T2 
WHERE T2.box && %(box_1)s))

在那里你可以看到我在 FROM 子句中重复的内容.它是如何正确的?

There you can see what i have duplicate in FROM clause. How did it correctly?

推荐答案

我找到了解决方案！

func.array(select([T2.id]).where(T2.box.op('&&')(box)).as_scalar())

添加 as_scalar() 后一切正常，因为在我的选择中，所有 id 都需要在一个数组中.

After added as_scalar() all be good, beacause in my select all ids need have in one array.

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