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“INSERT IGNORE” vs “INSERT … ON DUPLICATE KEY UPDATE”
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1003
I would recommend using INSERT...ON DUPLICATE KEY UPDATE.
If you use INSERT IGNORE, then the ro...
Does Ruby regular expression have a not match operator like “!~” in Perl?
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3 Answers
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Active
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Resize image proportionally with MaxHeight and MaxWidth constraints
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3 Answers
3
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Move all files except one
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143
If you use bash and have the extglob shell option set (which is usually the case):
mv ~/Linux/O...
What's the difference between a proc and a lambda in Ruby?
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An example:
p = Proc.new {|a, b| puts a**2+b**2 } # => #<Proc:0x3c7d28@(irb):1>
p.call 1, 2 # => 5
p.call 1 # => NoMethodError: undefined method `**' for nil:NilClass
p.call 1, 2, 3 # => 5
l = lambda {|a, b| puts a**2+b**2 } # => #<Proc:0x15016c@(irb):5 (lambda)>
l.ca...
linux 下巧妙使用squid代理服务器 - 更多技术 - 清泛网 - 专注C/C++及内核技术
...点。
1．共享网络
2．加快访问速度，节约通信带宽
3．防止内部主机受到攻击
4．限制用户访问，完善网络管理
原理：
① 客户端A向代理服务器提出访问Internet的请求。
② 代理服务器接受到请求后，首先与访问控制列...
What is tail recursion?
...ple function that adds the first N natural numbers. (e.g. sum(5) = 1 + 2 + 3 + 4 + 5 = 15).
Here is a simple JavaScript implementation that uses recursion:
function recsum(x) {
if (x === 1) {
return x;
} else {
return x + recsum(x - 1);
}
}
If you called recsum(5), th...
Select every Nth element in CSS
...;/h1>
<div>1</div> <div>2</div>
<div>3</div> <div>4</div>
<h2></h2>
<div>5</div> <div>6</div>
<div>7</div> <div>8</div>
<h2></h2>
<div>9</div> <...
Choosing a file in Python with simple Dialog
...ng tkinter?
from Tkinter import Tk # from tkinter import Tk for Python 3.x
from tkinter.filedialog import askopenfilename
Tk().withdraw() # we don't want a full GUI, so keep the root window from appearing
filename = askopenfilename() # show an "Open" dialog box and return the path to the select...