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How do I handle too long index names in a Ruby on Rails ActiveRecord migration?
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Provide the :name option to add_index, e.g.:
add_index :studies,
["user_id", "university_id", "subject_name_id", "subject_type_id"],
:unique => true,
:name => 'my_index'
If using the :index option on references in a create_table block, it t...
Drop multiple tables in one shot in mysql
...e A has two children B and C. Then we can use the following syntax to drop all tables.
DROP TABLE IF EXISTS B,C,A;
This can be placed in the beginning of the script instead of individually dropping each table.
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Most efficient way to reverse a numpy array
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When you create reversed_arr you are creating a view into the original array. You can then change the original array, and the view will update to reflect the changes.
Are you re-creating the view more often than you need to? You should be able to...
What does Java option -Xmx stand for? [duplicate]
...it says,
-Xmxn
Specify the maximum size, in bytes, of the memory allocation pool. This value must a multiple of 1024 greater than 2MB. Append the letter k or K to indicate kilobytes, or m or M to indicate megabytes. The default value is 64MB. The upper limit for this value will be approxim...
How to find if an array contains a specific string in JavaScript/jQuery? [duplicate]
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You really don't need jQuery for this.
var myarr = ["I", "like", "turtles"];
var arraycontainsturtles = (myarr.indexOf("turtles") > -1);
Hint: indexOf returns a number, representing the position where the specified searchv...
Enabling WiFi on Android Emulator
...s a
simulated Wi-Fi access point ("AndroidWifi"), and Android
automatically connects to it.
More Information:
https://developer.android.com/studio/run/emulator.html#wifi
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When should null values of Boolean be used?
Java boolean allows values of true and false while Boolean allows true , false , and null . I have started to convert my boolean s to Boolean s. This can cause crashes in tests such as
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Is there a method to generate a UUID with go language
...ic range. rand.Read returns random bytes in the range 0-255, which are not all valid values for a UUID. As far as I can tell, this should be done for all the values in the slice though.
If you are on linux, you can alternatively call /usr/bin/uuidgen.
package main
import (
"fmt"
"log"
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Difference between and
...s will not submit a form - they don't do anything by default. They're generally used in conjunction with JavaScript as part of an AJAX application.
<input type="submit"> buttons will submit the form they are in when the user clicks on them, unless you specify otherwise with JavaScript.
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Secure random token in Node.js
...oding in node is not url-safe, it includes / and + instead of - and _ . Therefore, the easiest way to generate such token I've found is
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