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MySQL select 10 random rows from 600K rows fast
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Yes, if you have potentially big gaps in ID's then the chance of your lowest ID's being picked randomly is much lower than your high IDs. In fact the chance that the first ID after the biggest gap getting picked is actually the highest. Therefore th...
Check if an array is empty or exists
...y" !== "array"
typeof array == "undefined"; // => true
Case Null
Generally speaking, null is state of lacking a value. For example a variable is null when you missed or failed to retrieve some data.
array = searchData(); // can't find anything
array == null; // => true
Case Not a...
Default argument values in JavaScript functions [duplicate]
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In javascript you can call a function (even if it has parameters) without parameters.
So you can add default values like this:
function func(a, b){
if (typeof(a)==='undefined') a = 10;
if (typeof(b)==='undefined') b = 20;
//your code
}
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Breaking out of a nested loop
...using goto is any worse than the normal use of something like break (after all they're both just unconditional branches to a label, it's just that with break the label is implicit).
– Greg Beech
Nov 28 '08 at 0:07
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Setting Django up to use MySQL
...ine, you can use
python manage.py runserver
Adding the ip:port argument allows machines other than your own to access your development application. Once you are ready to deploy your application, I recommend taking a look at the chapter on Deploying Django on the djangobook
Mysql default characte...
Tool for generating railroad diagram used on json.org [closed]
...string and value using string ::= ... and value ::= ... The references are all shown.
Check out some of the example diagrams on the page. They have XML and even EBNF itself.
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Styling HTML email for Gmail
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}
</style>
<xml>
<o:OfficeDocumentSettings>
<o:AllowPNG/>
<o:PixelsPerInch>96</o:PixelsPerInch>
</o:OfficeDocumentSettings>
</xml>
<![endif]-->
This is just a simple example, but, who know, it might come in handy some time.
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How can I find an element by CSS class with XPath?
.../div[contains(concat(' ', @class, ' '), ' Test ')]
If you wished to be really certain that it will match correctly, you could also use the normalize-space function to clean up stray whitespace characters around the class name (as mentioned by @Terry):
//div[contains(concat(' ', normalize-space(@...
Tetris-ing an array
...a include the algorithm to find the longest common prefix, thus making actually using a tree structure unnecessary? Ie why check the tree for multiple children when you could detect that while building the tree. Why then a tree at all? I mean if you start with an array already. If you can change the...
How to compare two floating point numbers in Bash?
...true or false.
Please, ensure that the bc basic calculator package is installed.
This equally works for floats in scientific format, provided a capital letter E is employed, e.g. num1=3.44E6
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