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MySQL Conditional Insert
... DBMS does not impose limitations on which table you select from when you em>x m>ecute an insert, try:
INSERT INTO m>x m>_table(instance, user, item)
SELECT 919191, 123, 456
FROM dual
WHERE NOT Em>X m>ISTS (SELECT * FROM m>x m>_table
WHERE user = 123
...
Use of 'prototype' vs. 'this' in JavaScript?
...
The em>x m>amples have very different outcomes.
Before looking at the differences, the following should be noted:
A constructor's prototype provides a way to share methods and values among instances via the instance's private [[Prot...
What part of Hindley-Milner do you not understand?
...orizontal bar means that "[above] implies [below]".
If there are multiple em>x m>pressions in [above], then consider them anded together; all of the [above] must be true in order to guarantee the [below].
: means has type
∈ means is in. (Likewise ∉ means "is not in".)
Γ is usually used to refer to a...
STL 算法 - C/C++ - 清泛网 - 专注C/C++及内核技术
...mplate<class InIt1, class InIt2> bool equal(InIt1 first, InIt1 last, InIt2 m>x m>);
template<class InIt1, class InIt2, class Pred> bool equal(InIt1 first, InIt1 last, InIt2 m>x m>, Pred pr);
includes
<algorithm>
判断第一个指定范围内的所有元素是否都被第二个范围包含...
What's the difference between a prom>x m>y server and a reverse prom>x m>y server? [closed]
What is the difference between a prom>x m>y server and a reverse prom>x m>y server?
21 Answers
2...
How to apply a function to two columns of Pandas dataframe
...
Here's an em>x m>ample using apply on the dataframe, which I am calling with am>x m>is = 1.
Note the difference is that instead of trying to pass two values to the function f, rewrite the function to accept a pandas Series object, and then inde...
numpy: most efficient frequency counts for unique values in an array
....org/doc/numpy/reference/generated/numpy.bincount.html
import numpy as np
m>x m> = np.array([1,1,1,2,2,2,5,25,1,1])
y = np.bincount(m>x m>)
ii = np.nonzero(y)[0]
And then:
zip(ii,y[ii])
# [(1, 5), (2, 3), (5, 1), (25, 1)]
or:
np.vstack((ii,y[ii])).T
# array([[ 1, 5],
[ 2, 3],
[ 5, ...
Ternary Operators in JavaScript Without an “Else”
...
First of all, a ternary em>x m>pression is not a replacement for an if/else construct - its an equivalent to an if/else construct that returns a value. That is, an if/else clause is code, a ternary em>x m>pression is an em>x m>pression, meaning that it returns a va...
Is gcc's __attribute__((packed)) / #pragma pack unsafe?
...entially unsafe on some systems. The symptom probably won't show up on an m>x m>86, which just makes the problem more insidious; testing on m>x m>86 systems won't reveal the problem. (On the m>x m>86, misaligned accesses are handled in hardware; if you dereference an int* pointer that points to an odd address, i...