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MySQL join with where clause
...N user_category_subscriptions ON
user_category_subscriptions.category_id = categories.category_id
and user_category_subscriptions.user_id =1
See, with an inner join, putting a clause in the join or the where is equivalent. However, with an outer join, they are vastly different.
As a join...
Is SQL or even TSQL Turing Complete?
...e true programming languages, so that's kinda cheating).
In this set of slides Andrew Gierth proves that with CTE and Windowing SQL is Turing Complete, by constructing a cyclic tag system, which has been proved to be Turing Complete. The CTE feature is the important part however -- it allows you to...
Change the name of the :id parameter in Routing resources for Rails
...he post is https://thoughtbot.com/blog/rails-patch-change-the-name-of-the-id-parameter-in
5 Answers
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UPDATE multiple tables in MySQL using LEFT JOIN
...
UPDATE t1
LEFT JOIN
t2
ON t2.id = t1.id
SET t1.col1 = newvalue
WHERE t2.id IS NULL
Note that for a SELECT it would be more efficient to use NOT IN / NOT EXISTS syntax:
SELECT t1.*
FROM t1
WHERE t1.id NOT IN
(
SELECT id
...
SQL query for finding records where count > 1
I have a table named PAYMENT . Within this table I have a user ID, an account number, a ZIP code and a date. I would like to find all records for all users that have more than one payment per day with the same account number.
...
Unable to copy ~/.ssh/id_rsa.pub
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DISPLAY=:0 xclip -sel clip < ~/.ssh/id_rsa.pub didn't work for me (ubuntu 14.04), but you can use :
cat ~/.ssh/id_rsa.pub
to get your public key
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How do I validate a date string format in python?
...('2003-12-23')
>>> validate('2003-12-32')
Traceback (most recent call last):
File "<pyshell#20>", line 1, in <module>
validate('2003-12-32')
File "<pyshell#18>", line 5, in validate
raise ValueError("Incorrect data format, should be YYYY-MM-DD")
ValueError: In...
Print Current Mercurial Revision Hash?
...
Try:
hg id -i
Example:
$ hg id -i
adc56745e928
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When to use window.opener / window.parent / window.top
...
window.opener refers to the window that called window.open( ... ) to open the window from which it's called
window.parent refers to the parent of a window in a <frame> or <iframe>
window.top refers to the top-most window from a window nested in one or m...
Authoritative position of duplicate HTTP GET query keys
...
This is based on an attack called HTTP Parameter Pollution and has been analyzed by OWASP: owasp.org/images/b/ba/AppsecEU09_CarettoniDiPaola_v0.8.pdf At page 9 you'll find a list of 20 systems and a description how they handle this issue.
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