如何解決「近‘與’：語法錯誤」

Question

我試圖重現SQLAlchemy的文檔頁面上找到this查詢遞歸查詢CTE（瓶/ SQLAlchemy的）。設立在models.py的Part下課後，這是我有：

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，這給出了一個錯誤：

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',)] 

生成的查詢（複製從錯誤信息粘貼）看起來是這樣的：

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（在不同的地方換行的可讀性）：

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，作爲比較，這裏的SQLAlchemy的文檔link純PostgreSQL的查詢：

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查詢之間看到的唯一差別（我認爲應該工作）和我正在生成的一個是：

1. 所有額外的 「AS」 語句（SELECT parts.sub_part AS sub_part VS SELECT sub_part）
2. 不同的格式（生成的查詢^ h換行符怪異點 - 例如，UNION ALL和SELECT）

但是，據我可以告訴之間沒有斷行，這些都不應該導致語法錯誤... 我也試過執行Postgre查詢作爲原始SQL（雖然SQLAlchemy使用sqlite3，顯然，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() 

但我仍然收到語法錯誤。

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"] 

我也嘗試重新格式化生成的查詢並將其作爲原始SQL執行，結果類似。

最後，我試圖寫的SQLite查詢和執行它：

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 

這也拋出一個語法錯誤。

在這一點上，我真的不知道該怎麼辦...好像連WITH查詢有正確的語法仍然會拋出一個錯誤。我知道，遞歸CTE查詢在SQLAlchemy的支持，根據文檔，並根據此（_http：//stackoverflow.com/a/24780445）回答這裏。老實說，我不知道爲什麼所有這些疑問都被認爲有錯誤的語法。我的python代碼與文檔中的示例幾乎完全相同。

我需要安裝的東西WITH RECURSIVE在SQLAlchemy的工作？我的語法實際上錯了嗎？在這裏失去了很多，任何幫助表示讚賞。我希望我可以說我已經取得了一些進展，但我幾乎不知道該怎麼做，這是PostgreSQL vs SQLite的問題嗎？有沒有人有我想要做的，我可以看看的工作示例？）

Answer 1

問題是，您正在運行sqlite3的舊版本（如#sqlalchemy討論）;你有3.8.2，並且在3.8.3中增加了CTE支持。