大约有 40,000 项符合查询结果（耗时：0.0335秒） [XML]
MongoDB SELECT COUNT GROUP BY
...ier way to do it using aggregate:
db.contest.aggregate([
{"$group" : {_id:"$province", count:{$sum:1}}}
])
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Add Foreign Key to existing table
...
To add a foreign key (grade_id) to an existing table (users), follow the following steps:
ALTER TABLE users ADD grade_id SMALLINT UNSIGNED NOT NULL DEFAULT 0;
ALTER TABLE users ADD CONSTRAINT fk_grade_id FOREIGN KEY (grade_id) REFERENCES grades(id);
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What are Flask Blueprints, exactly?
...laster of your application.
# An example
from flask import Blueprint
tree_mold = Blueprint("mold", __name__)
@tree_mold.route("/leaves")
def leaves():
return "This tree has leaves"
@tree_mold.route("/roots")
def roots():
return "And roots as well"
@tree_mold.route("/rings")
@tree_mold.r...
How to check if a map contains a key in Go?
...thout worrying about the actual
value, you can use the blank identifier (_) in place of the usual
variable for the value.
_, present := timeZone[tz]
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Can I find events bound on an element with jQuery?
...
In modern versions of jQuery, you would use the $._data method to find any events attached by jQuery to the element in question. Note, this is an internal-use only method:
// Bind up a couple of event handlers
$("#foo").on({
click: function(){ alert("Hello") },
mous...
Max length UITextField
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With Swift 5 and iOS 12, try the following implementation of textField(_:shouldChangeCharactersIn:replacementString:) method that is part of the UITextFieldDelegate protocol:
func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) ->...
Some built-in to pad a list in python
...
a += [''] * (N - len(a))
or if you don't want to change a in place
new_a = a + [''] * (N - len(a))
you can always create a subclass of list and call the method whatever you please
class MyList(list):
def ljust(self, n, fillvalue=''):
return self + [fillvalue] * (n - len(self))
a...
Why doesn't requests.get() return? What is the default timeout that requests.get() uses?
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Thanks, doing print(requests.request.__doc__) in IPython is more of what I was looking for though. I was wondering what other optional arguments to request.get() there were.
– wordsforthewise
Oct 22 '17 at 21:16
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Algorithm to detect overlapping periods [duplicate]
... throw new Exception("Invalid range edges.");
}
_Start = start;
_End = end;
}
#endregion
#region Properties
private DateTime _Start;
public DateTime Start {
get { return _Start; }
private set { _Start = value; }
}
priva...
What is the use of “assert” in Python?
...eter.
As for disabling them, when running python in optimized mode, where __debug__ is False, assert statements will be ignored. Just pass the -O flag:
python -O script.py
See here for the relevant documentation.
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