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What is the difference between JOIN and UNION?
... subsets it -- completely different operations. Trivial example of UNION:
mysql> SELECT 23 AS bah
-> UNION
-> SELECT 45 AS bah;
+-----+
| bah |
+-----+
| 23 |
| 45 |
+-----+
2 rows in set (0.00 sec)
similary trivial example of JOIN:
mysql> SELECT * FROM
-> (SELECT...
Map enum in JPA with fixed values?
...nverter.
Create an enumerated class like so:
public enum NodeType {
ROOT("root-node"),
BRANCH("branch-node"),
LEAF("leaf-node");
private final String code;
private NodeType(String code) {
this.code = code;
}
public String getCode() {
return code;
...
Simulate delayed and dropped packets on Linux
...y to all packets going out of the local Ethernet.
# tc qdisc add dev eth0 root netem delay 100ms
Now a simple ping test to host on the local network should show an increase of 100 milliseconds. The delay is limited by the clock resolution of the kernel (Hz). On most 2.4 systems, the system cl...
Emulator error: This AVD's configuration is missing a kernel file
...r the SDK files and will look something like:
emulator: found ANDROID_SDK_ROOT: C:\Program Files (x86)\Android\android-sdk
Make sure that location is correct.
In my case, ANDROID_SDK_ROOT was initially set incorrectly to my home directory. This is because I set it that way by blindly following t...
Execute a terminal command from a Cocoa app
...n use this method like this:
NSString *output = runCommand(@"ps -A | grep mysql");
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Get Output From the logging Module in IPython Notebook
...y creating a
StreamHandler with a default Formatter and adding it to the root
logger. The functions debug(), info(), warning(), error() and
critical() will call basicConfig() automatically if no handlers are
defined for the root logger.
This function does nothing if the root logger alre...
How does RewriteBase work in .htaccess
...writeBase, Apache usually detects it correctly for paths under the DocumentRoot unless:
You are using Alias directives
You are using .htaccess rewrite rules to perform HTTP redirects (rather than just silent rewriting) to relative URLs
In these cases, you may find that you need to specify the Re...
Do I need to create indexes on foreign keys on Oracle?
...int creates also an index... i.e. Jet Engine (MSAccess files, Firebird and MySQL)
– bubi
Apr 23 '15 at 15:19
17
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Setting up FTP on Amazon Cloud Server [closed]
...d pam config also checks /etc/vsftpd/ftpusers
# for users that are denied.
root
bin
daemon
adm
lp
sync
shutdown
halt
mail
news
uucp
operator
games
nobody
This is basically saying, "Don't allow these users FTP access." vsftpd will allow FTP access to any user not on this list.
So, in order to cre...
Sublime as default editor
...
Open regedit (Win+R, type "regedit", select OK).
Navigate to HKEY_CLASSES_ROOT\Applications\sublime_text.exe\shell\open\command
Verify that the path is accurate, correct it if it is not. Exit regedit.
Open task manager via Ctrl+Alt+Del (or Ctrl+Shift+Esc for later versions of Windows), kill explore...