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SQL to determine minimum sequential days of access?
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@Artem: That was what I initially thought but when I thought about it, if you have an index on (UserId, CreationDate), the records will show up consecutively in the index and it should perform well.
– Mehrdad Afshari
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How to extract the decision rules from scikit-learn decision-tree?
...sion of sklearn, because some values of tree.tree_.feature are -2 (specifically for leaf nodes).
There is no need to have multiple if statements in the recursive function, just one is fine.
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Python: most idiomatic way to convert None to empty string?
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If you actually want your function to behave like the str() built-in, but return an empty string when the argument is None, do this:
def xstr(s):
if s is None:
return ''
return str(s)
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What is a proper naming convention for MySQL FKs?
...constraints. If a name is not given, InnoDB creates a unique name automatically.
In any case, this is the convention that I use:
fk_[referencing table name]_[referenced table name]_[referencing field name]
Example:
CREATE TABLE users(
user_id int,
name varchar(100)
);
CREATE T...
MongoDB/Mongoose querying at a specific date?
...onents. To query those times you need to create a date range that includes all moments in a day.
db.posts.find( //query today up to tonight
{"created_on": {"$gte": new Date(2012, 7, 14), "$lt": new Date(2012, 7, 15)}})
s...
Max length UITextField
... that can be entered into a UITextField using swift? , I saw that if I use all 10 characters, I can't erase the character too.
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Best way to iterate through a Perl array
...ay elements occurs. ($_ is aliased to the element in #1, but #2 and #3 actually copy the scalars from the array.)
#5 might be similar.
In terms memory usage: They're all the same except for #5.
for (@a) is special-cased to avoid flattening the array. The loop iterates over the indexes of the array...
Cross-Origin Request Headers(CORS) with PHP headers
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Access-Control-Allow-Headers does not allow * as accepted value, see the Mozilla Documentation here.
Instead of the asterisk, you should send the accepted headers (first X-Requested-With as the error says).
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How to get a variable name as a string in PHP?
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Actually now that I've tested my code, my code always returned 'var' because it's being used in the function. When I use $GLOBALS instead, it returns the correct variable name for some reason. So I'll change the above code to use...
Remove duplicates from an array of objects in JavaScript
...) dot notation. Yours is ES5 syntax. The others are mostly ES6 (ECMA2015). All are valid in 2017. See jaredwilli's comment.
– agm1984
Nov 15 '17 at 9:20
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