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add column to mysql table if it does not exist
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Note that INFORMATION_SCHEMA isn't supported in MySQL prior to 5.0. Nor are stored procedures supported prior to 5.0, so if you need to support MySQL 4.1, this solution isn't good.
One solution used by frameworks that use database migrations is...
How can I find which tables reference a given table in Oracle SQL Developer?
...in ('P', 'U')
and table_name = :r_table_name
and owner = :r_owner
)
order by table_name, constraint_name
Where r_owner is the schema, and r_table_name is the table for which you are looking for references. The names are case sensitive
Be careful because on the reports tab of Oracle SQL D...
Twitter image encoding challenge [closed]
...um number of bits you can encode in a single utf8 character is 31 bits. In order to do this, I would use all characters that are in the U-04000000 – U-7FFFFFFF range. (1111110x 10xxxxxx 10xxxxxx 10xxxxxx 10xxxxxx 10xxxxxx, there are 31 x's, therefore I could encode up to 31 bits).
31 bits times 14...
Socket.IO - how do I get a list of connected sockets/clients?
...lients('room');
anymore. Instead you can use the following
var clients_in_the_room = io.sockets.adapter.rooms[roomId];
for (var clientId in clients_in_the_room ) {
console.log('client: %s', clientId); //Seeing is believing
var client_socket = io.sockets.connected[clientId];//Do whatever y...
Iterate a list as pair (current, next) in Python
...
Since the_list[1:] actually creates a copy of the whole list (excluding its first element), and zip() creates a list of tuples immediately when called, in total three copies of your list are created. If your list is very large, you ...
How can I hash a password in Java?
...m recommended cost, used by default
*/
public static final int DEFAULT_COST = 16;
private static final String ALGORITHM = "PBKDF2WithHmacSHA1";
private static final int SIZE = 128;
private static final Pattern layout = Pattern.compile("\\$31\\$(\\d\\d?)\\$(.{43})");
private final Se...
How do you test that a Python function throws an exception?
...t ahold of the actual Exception object thrown:
import unittest
def broken_function():
raise Exception('This is broken')
class MyTestCase(unittest.TestCase):
def test(self):
with self.assertRaises(Exception) as context:
broken_function()
self.assertTrue('This i...
How can I calculate the number of lines changed between two commits in git?
...han what he mentions. Since git log internally calls the diff machinery in order to print requested information, you can give it any of the diff stat options - not just --shortstat. What you likely want to use is:
git log --author="Your name" --stat <commit1>..<commit2>
but you can us...
What 'additional configuration' is necessary to reference a .NET 2.0 mixed mode assembly in a .NET 4
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In order to use a CLR 2.0 mixed mode assembly, you need to modify your App.Config file to include:
<?xml version="1.0"?><configuration> <startup useLegacyV2RuntimeActivationPolicy="true"> <supportedRunt...
Pythonic way to print list items
...myList, sep='\n')
You can get the same behavior on Python 2.x using from __future__ import print_function, as noted by mgilson in comments.
With the print statement on Python 2.x you will need iteration of some kind, regarding your question about print(p) for p in myList not working, you can just...