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Use email address as primary key?
Is email address a bad candidate for primary when compared to auto incrementing numbers?
25 Answers
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How to get temporary folder for current user
...n checks for the existence of environment variables in the following order and uses the first path found:
The path specified by the TMP environment variable.
The path specified by the TEMP environment variable.
The path specified by the USERPROFILE environment variable.
The Windows directory.
It'...
How to calculate cumulative normal distribution?
...f(-1.96)
0.024997895148220435
In other words, approximately 95% of the standard normal interval lies within two standard deviations, centered on a standard mean of zero.
If you need the inverse CDF:
>>> norm.ppf(norm.cdf(1.96))
array(1.9599999999999991)
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How to set the JDK Netbeans runs on?
I have older NB6.7, NB6.9, NB7.0, which used to run on jdk1.6.0_21 and jdk1.6.0_25. Now I've removed those JDKs and only have jdk1.6.0_26 and jdk1.7.0 left, but I still want to keep the older NBs, but now when I run them, I get this message:
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How to Deep clone in javascript
...first, a code example which clones object literals, any primitives, arrays and DOM nodes.
function clone(item) {
if (!item) { return item; } // null, undefined values check
var types = [ Number, String, Boolean ],
result;
// normalizing primitives if someone did new String('a...
What should I do when 'svn cleanup' fails?
I have a lot of changes in a working folder, and something screwed up trying to do an update.
30 Answers
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How to set environment variables from within package.json
... variables from within package.json to be used with npm start like commands?
14 Answers
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Get current domain
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just print_r(apache_request_headers()) and you'll understand all :)
– onehalf
Nov 25 '15 at 11:01
2
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Adding a column to an existing table in a Rails migration
...ontaining line:
add_column :users, email, string
Then do a rake db:migrate and it'll run the new migration, creating the new column.
If you have not yet run the original migration you can just edit it, like you're trying to do. Your migration code is almost perfect: you just need to remove the add_...
How do I create an empty array/matrix in NumPy?
...t I would normally use a list. I want to create an empty array (or matrix) and then add one column (or row) to it at a time.
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