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MySQL, Check if a column exists in a table with SQL

...pecific column, and if not — create it. Otherwise do nothing. This is really an easy procedure in any enterprise-class database, yet MySQL seems to be an exception. ...
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Extract substring in Bash

...o-based) and "5" is the length. Also, +1 for @gontard 's link that lays it all out! – Doktor J Sep 12 '14 at 17:32 ...
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How do you serialize a model instance in Django?

... You can easily use a list to wrap the required object and that's all what django serializers need to correctly serialize it, eg.: from django.core import serializers # assuming obj is a model instance serialized_obj = serializers.serialize('json', [ obj, ]) ...
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How to [recursively] Zip a directory in PHP?

...ce), file_get_contents($source)); } return $zip->close(); } Call it like this: Zip('/folder/to/compress/', './compressed.zip'); share | improve this answer | ...
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UITableViewCell, show delete button on swipe

... During startup in (-viewDidLoad or in storyboard) do: self.tableView.allowsMultipleSelectionDuringEditing = NO; Override to support conditional editing of the table view. This only needs to be implemented if you are going to be returning NO for some items. By default, all items are editable....
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How to validate an e-mail address in swift?

...s quite funny that ............ as well as (1) the regex being utterly, totally incorrect (2) the regex (even within the context of what it's trying to do) has major errors (3) the Swift is wrong (4) even setting that aside, the style is totally wrong (5) not that it matters given all the rest but i...
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Exif manipulation library for python [closed]

...mation from Jpeg and Tiff files which include it. This information is typically included in images created using digital imaging devices such as digital cameras, digital film scanners, etc. However, it looks like pyexif hasn't been updated in quite while. They recommend if theirs isn't doing the ...
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Find an item in List by LINQ?

Here I have a simple example to find an item in a list of strings. Normally I use for loop or anonymous delegate to do it like this: ...
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What does the JSLint error 'body of a for in should be wrapped in an if statement' mean?

... First of all, never use a for in loop to enumerate over an array. Never. Use good old for(var i = 0; i<arr.length; i++). The reason behind this is the following: each object in JavaScript has a special field called prototype. Ever...
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Best practice: PHP Magic Methods __set and __get [duplicate]

...magic methods. This was a mistake, the last part of your question says it all : this is slower (than getters/setters) there is no auto-completion (and this is a major problem actually), and type management by the IDE for refactoring and code-browsing (under Zend Studio/PhpStorm this can be handle...