python-3.x - 更新 SQLite 不会改变 python

Question

我的代码运行，但更新不坚持：

conn.execute('''UPDATE COMBINATIONS \
SET METRIC = COMBINATIONS.FREQ_EVER / help.DOCS_EVER \
FROM (SELECT DOCS_EVER, TERM FROM TERMS) AS help WHERE COMBINATIONS.SEARCH = help.TERM;''')
conn.commit()

因此，当我执行以下操作时：

test = conn.execute('''SELECT METRIC FROM COMBINATIONS WHERE SEARCH = "and" AND SUGGESTED = "in"''')
for row in test:
    print(row)

.. 我只得到我的旧默认值。任何人都知道为什么以及如何解决它？

我尝试了以下方法来检查是否从语句的 SELECT 版本中获得结果，并且确实得到了很多结果：

test = conn.execute('''SELECT * FROM COMBINATIONS, (SELECT DOCS_EVER, TERM FROM TERMS) AS help WHERE COMBINATIONS.SEARCH = help.TERM;''')
for row in test:
     print(row)

我在 python 中使用 sqlite3 包。它是 SQLite 版本 3.32.2。