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postgresql - add boolean column to table set default
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Note that if your table is big this can take a long time and lock the table for the entire time. It's faster to split it into steps: add the column without a default with ALTER TABLE users ADD COLUMN priv_user BOOLEAN;, then UPDATE users SET priv_user = 'f'; and finally if you need...
How can I view the source code for a function?
...S4 method dispatch system
The S4 system is a newer method dispatch system and is an alternative to the S3 system. Here is an example of an S4 function:
> library(Matrix)
Loading required package: lattice
> chol2inv
standardGeneric for "chol2inv" defined from package "base"
function (x, ...)...
Find first element in a sequence that matches a predicate
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I am a python newbie and read the docs and the ifilter uses the "yield" method. I assume this means that the predicate is lazily evaluated as we go. i.e, we dont run the predicate through the entire list because I have a predicate function that i...
Local Storage vs Cookies
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Cookies and local storage serve different purposes. Cookies are primarily for reading server-side, local storage can only be read by the client-side. So the question is, in your app, who needs this data — the client or the server?
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Why is document.write considered a “bad practice”?
I know document.write is considered bad practice; and I'm hoping to compile a list of reasons to submit to a 3rd party vendor as to why they shouldn't use document.write in implementations of their analytics code.
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Html.Textbox VS Html.TextboxFor
What is the difference between Html.Textbox and Html.TextboxFor?
4 Answers
4
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Gradle, Android and the ANDROID_HOME SDK location
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In
/my_current_project/
I've created a file called local.properties and put inside
sdk.dir=/my_current_path_to/sdk
In the console I need to do
set ANDROID_HOME=/my_current_path_to/sdk
Hope this helps.
shar...
Operation on every pair of element in a list
...x, y)
Edit: There are two very similar functions as well, permutations() and combinations(). To illustrate how they differ:
product() generates every possible pairing of elements, including all duplicates:
1,1 1,2 1,3 1,4
2,1 2,2 2,3 2,4
3,1 3,2 3,3 3,4
4,1 4,2 4,3 4,4
permutation...
Is there a “vim runtime log”?
Sometimes I try a customization/command in my vimrc. Everything seens to be correct, but it just doesn't work.
6 Answers
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How to display a confirmation dialog when clicking an link?
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Inline event handler
In the most simple way, you can use the confirm() function in an inline onclick handler.
<a href="delete.php?id=22" onclick="return confirm('Are you sure?')">Link</a>
Advanced event handling
But normal...