How to get list from MySql in python?

Question

I am nex to python and want to retrieve values from MySQL into a list in python 3.x:

curb.execute("SELECT URL FROM test")
URLs_old = curb.fetchall()

results in:

[('https://www.test.de',), ('https://www.bla.de',)]

while I would need:

['https://www.test.de', 'https://www.bla.de']

How can the later one be achived?

Jan · Accepted Answer · 2020-06-18 07:27:31Z

2

You can always do

lst1 = [('https://www.test.de',), ('https://www.bla.de',)]
lst2 = [item for tpl in lst1 for item in tpl]
print(lst2)
# ['https://www.test.de', 'https://www.bla.de']

There might exist functions that return a list immediately though (haven't checked).

answered Jun 18, 2020 at 7:27

Jan

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2 Comments

merlin Over a year ago

That seems to work as it looks like the list I need, but Python returns the error when I try using it: "TypeError: unhashable type: 'list'". Context is scrapy rules, where I try to add URLs I want to deny: Rule( LinkExtractor( allow=['^.*\\d+/[a-z0-9-]+\.html$'], deny=[URLs_old] ), callback='parse_item', follow=True ),

MacOS Over a year ago

Maybe more readable [link for link_tuple in list for link in link_tuple]. :)

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