Programming :: MySQL - Get A Random Selection Of An Ordered Data Set
Jan 11, 2011
Given the following data structure: Quote:
[Code]...
What is the minimum possible MySQL query to get a random data selection that includes each Index number only once and ordered ascending. The maximum index number is known. For example running the query should get the following data: 01, 06, 07, 02. Running the query again, you may get the same data or another possible combination like: 01, 05, 07, 04. Of course you could run a loop for 1 to max_index and process a random ordered data selection until the next index number is found. But I think this will result in too many database access. Also you could run max_index queries to get all IDs that correspond to the given index and randomly select one ID for each index.
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Dec 8, 2009
I am currently trying to turn off ordered data mode for ext3 filesystem. I want to shred some files and apparently this won't work with journaling on.
I can't seem to find any good explanations of what exactly "ordered data" means in terms of data recovery/security...or at least none that are written in simple n00b terms. It is all written in terms of disk crashes and whether old data will mix in with the new. It doesn't say whether one's cousin will be able to poke around and find some thought-it-was-deleted porno if he's on the computer.
Can someone step me through the process of turning this off using tune2fs? (if that is the best way to do it!) Do I have to revert to ext2? Can I turn it back on later? Will I lose data (for example, does the drive need to be reformated?) once this change is made? And how does one find, read, and delete/shred the journal itself? Is "ordered data" even a real problem for data recovery?
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Jan 20, 2010
At boot time, before entering Runlevel 3 the HDD will go mad when mounting tmpfs on /dev/shm...
Code:
EXT3 FS on sda1, internal journal
EXT3-fs: mounted filesystem with ordered data mode
/dev/sda1 on /boot type ext3 (rw)
tmpfs on /dev/shm type tmpfs (rw)
INIT:Entering runlevel 3
It will go on and on at the tmpfs on /dev/shm type tmpfs (rw) until i press ctrl-C...then I will stop whatever it is doing, let the hdd rest a bit, and resume normal boot..
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Jul 19, 2010
I have set up a MySQL database which has only three fields for user-name, password and index number. But there is a LOT of data (thousands of columns) which would take too long to enter manually. I'm sure MySQL must have a file format whereby a single large file containing different data types can be successfully automatically imported and the various data elements distributed to their intended fields. Does anyone know which characters MySQL uses as field seperators for this formatting of data, or is there a program already written which can take raw data and organize it into a SQL compatible file?
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Aug 26, 2010
I have a CSV called source1 with data like:
Date12:00:00 AM12:30:00 AM01:00:00 AM01:30:00 AM02:00:00 AM02:30:00 AM03:00:00 AM ...
07/31/1051.5252.4852.6452.863.3663.8445.6 ...
08/01/1049.4449.9261.2860.1652.6449.1247.52 ...
08/02/1049.1248.9648.9650.7260.1658.0851.04 ...
08/03/1060.3260.6459.260.9637.9233.2832.8 ...
[Code].....
Also, the CSV file is updates every few hours and I need to load any new data from the file to the database without creating duplicates of data that has already been loaded to the database.
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Nov 8, 2010
I am trying to build an array with the column headers and the data like so:
PHP Code:
function query($query) {
$data = array();
$q = "$query";
$this->log->message("Manual query [$q], returning columns...");
$result = @mysqli_query($this->dbc, $q);
$this->selected_rows = mysqli_num_rows($result);
while($meta = mysqli_fetch_field($result)) {
while($row = mysqli_fetch_array($result, MYSQLI_ASSOC)) {
echo "meta [{$meta->name}]"; $data[$meta->name][] = $row[$meta->name]; } }
echo "DATA ["; print_r($data); echo "] <br />";
return $data; }
So I can select the data from the array like so:
PHP Code:
echo $data[col_name][row_num];
However when I dump the array I dont get the data I am expecting:
Code:
running select * from users:
meta [company_name]meta [company_name]
DATA [Array ( [company_name] => Array ( [0] => My company [1] => My details ) ) ]
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Nov 19, 2008
I have this program:
#! /usr/bin/perl
use DBI ;
use strict ;
[code]....
and I get this error simply running the program from the command line: DBD::mysql::st execute failed: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '' at line 1 at ./submit.cgi line 24.
is this the right syntax to use, both, for this line:
my (@param) = $cgi->param("firstname","lastname","type") ;
as well as this one:
$sth=$dbh->prepare ("SELECT firstname,lastname,type FROM dts WHERE firstname LIKE $param[0] AND lastname LIKE $param[1] and type LIKE $param[2]" );
or should there be quotes around the $param[0] or something? (also is it $param[0] or $param(0)?)
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Jul 5, 2011
If this post is correct [URL] I can expect that it will take more then 16 days to fill my 2TB partition from /dev/urandom. That's not workable for me. dd if=/dev/urandom of=/dev/sdxx has been running for 36 hours, and I need to finish setting up the filesystem. But I also need to make a "professional effort" at encrypting the partition. I am supposed to fill the partition with random data, to strengthen the encryption for a LUKS partition. It seems that if the bad guys get the drive, they have much more time to try and crack it, then I have to encrypt it. Ok, so I can try Code: sudo /sbin/badblocks -c 10240 -s -w -t random -v /dev/sdxx How long can I expect badblocks to run on a 2TB partition?.
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Jun 18, 2010
How can I change the behavior of the selection buffer or a program that uses it ( I have xclip) to not send me text until the mouse button is released while clicking and dragging? This causes havok in the software I'm developing that tries to make use of the selection buffer. I need the full selection, not bits more bits more bits and then the full selection.EDIT: I cannot listen for mouse events such as button release outside of the GUI of my program.
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Sep 22, 2010
Once random data is obtained by means other than a pseudo-random number generator, what software is available to measure the entropy or quality/randomness of the data?
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Mar 9, 2011
I want to view a hard drive and see if it has all zeroes, how would I do this? I want to view a hard drive and see if it has all random data, or random data mixed with zeroes. How can I do this? I prefer to do all this in linux if possible without a gui...so looking for any cli tools to view with.
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Jun 1, 2009
I just discovered that my server is sending huge amount of data out at about 1Mbps. My immediate thought was the deluge bittorrent client, however it is supposedly not running (and a check confirmed its total active torrents was set to 0). I turned off the network and went in to Firestarter to set the outbound traffic to restrictive, turned on network again and no more data was sent. A look in Firestarter / Events showed a long list of random ports being used (see further down). How can I identify what program is sending all the data?
In Firestarter it doesn't really say much more than the port. Not sure if it is some misconfigured program or a malware/virus. I just got my ADSL connected a few days ago, and before that I used a mobile broadband (3G) as I just relocated. During the period I used the 3G the server might have been without firewall for a few days and it was also at this time I discovered an increase in network traffic (but I didn't really pay much attention at that time). I am running Fedora 10.
List of events from firestarter, my server is 192.168.1.100:
Time:Jun 1 16:48:12 Direction: Outbound In: Out:eth1 Port:39435 Source:192.168.1.100 Destination:58.208.xxx.56 Length:129 TOS:0x00 Protocol:UDP Service:Unknown
Time:Jun 1 16:48:12 Direction: Outbound In: Out:eth1 Port:6990 Source:192.168.1.100 Destination:112.94.xxx.212 Length:129 TOS:0x00 Protocol:UDP Service:Unknown
Time:Jun 1 16:48:12 Direction: Outbound In: Out:eth1 Port:2973 Source:192.168.1.100 Destination:118.93.42.xxx Length:129 TOS:0x00 Protocol:UDP Service:Svnetworks .....
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Jan 31, 2011
I am creating an script with Xdialog.The checklist option is confusing me a litte. Can someone tell me how to save the checklist states so they can be used in a script? As an example:
Code:
Xdialog --checklist "Choose toppings:" 10 40 3
1 Cheese on
2 "Tomato Sauce" on
3 Anchovies off
I would then like to put these values through if/else statements to perform different things with respect to the user selection.
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Sep 18, 2010
I am creating a program that need menu with multi selection option for shell (CLI).I am using of Bash scripts.something that will look like that:
Menu:
[ ] option 1
[x] option 2
[code]...
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May 30, 2011
I am trying to install the bucktooth gopher server on a Windows xp laptop. I have cygwin 1.7 installed, and I recently installed the xinetd and perl packages. I successfully (?) configured bucktooth, but I have had trouble with the connection cutting out partway through (partial directory listings, half-blank pictures, etc.). I used tintin++ to get the connection's data directly, and found that in addition to occasionally missing lines, some lines are duplicated.
I then ran the bucktooth server directly (to bypass xinetd), and found that the server was giving consistent, correct output. I then added a test service to xinetd (m4), but after connecting to this test service (through tintin++), xinetd would respond with one line of unexpected data (such as "gf" or a line from a recent bucktooth directory listing) and close the connection. Could this be a broken xinetd? My xinetd configuration:
[Code]...
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Oct 18, 2010
I am trying to create an array that will allow me to print a list after selection such as:
1) Location A
2) Location B
3) Location C
Would you like to print selected locations? Print I have no idea how to approach this problem and don't know whether Perl, Bash or shell script would be the most useful in this particular situation.
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Aug 1, 2010
I'm trying to use buildroot to cross compile some libraries for me. To do so I've set up build root to point to my working tool chain in the menuconfig.All seems fine however when I try to make (buildroot) I get the following error
rm -rf /root/buildroot-2010.05/output/build/buildroot-config
mkdir -p /root/buildroot-2010.05/output/build
cp -dpRf package/config/buildroot-config /root/buildroot-2010.05/output/build/buildroot-config
Checking external toolchain settings
Incorrect selection of the C library
make: *** [/root/buildroot-2010.05/output/stamps/ext-toolchain-installed] Error 255
I know it's pointing to the correct files and gcc as any wrong paths are reported in make menuconfig.
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Feb 28, 2011
How can I generate a list of files in a directory [e.g.: "/mnt/hdd/PUB/"] ordered by the files modification time? [in descending order, the oldest modified file is at the lists end]
ls -A -lRt would be great:[URL]
But if a file is changed in a directory it lists the full directory...so the pastebined link isn't good [i don't want a list ordered by "directories", I need a "per file" ordered list]
OS: openwrt..[no perl -> not enough space for it :( + no "stat", or "file" command]
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Jun 11, 2009
I am using read() in c++ to get data from a serial port. However, if no data is available on the serial port the function blocks until dta arrives.Example code:
//------------------------------------------------------------
char m_readBuffer[255] = {0};
char* p_curChar = m_readBuffer;
[code]...
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May 9, 2010
I have some data files that should be distributed with my program. Using dist_pkgdata_DATA in Makefile.am, I get these files installed to /usr/local/data/share/package-name. The problem is that data is read-only, and my program needs to modify it. Playing with dist_sharedstate_DATA, dist_localstate_DATA, dist-data_DATA varibles, I got different installation directories, like /usr/local/com, usr/local/var, but data is always read-only.
How can I distribute modifiable data files with my package? I need some common directory for all users, or maybe local data in a user directory.
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Dec 25, 2009
I have just upgraded my old CentOS system,but something goes wrong(1) I can not enter database to MySQL from web page,and I had a "add new contact info" available there before .(2) I want to install SugarCRM to my web page,but SugarCRM can't create database with the right username and password . Other thing is OK, I can get data from MySQL from web page. Here is the package I have : php-5.1.6-3.el4s1.10 mysql-5.0.82sp1-1.el4_8
Does it because that these two packages don't match each other?
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Jan 7, 2010
i have installed ubuntu server 64bit with lamp so all in one (apache, mysql and php) and i need to downgrade mysql because of serious problems with mysql 5.1 and this is the only solution. But i need to be working with apatche and php also and have my.ini like i have now (can backup it) so is there any save way to do that?
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Nov 6, 2010
Ubuntu 10.04. I've tried every method I can find and none work. Here's what I know...
1. My /etc/my.cnf is ignored. I can even delete it and phpmyadmin continues to work as it did before.
2. If I move /var/lib/mysql and replace it with a new directory (chowned to mysql:mysql so it looks like it's got the same ownership & permissions as the original) I get a write permission problem, e.g.
Quote:
What I ultimately want to do is used existing database files on a FAT32 partition but I can't even get to first base.
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May 6, 2010
I want to import data from MySQL to MSSQL. I've been searching in the web, and I can't find a good and straight answer. How can I do it?
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Jul 18, 2011
how i can copy data from mysql server to local system or samba server. I want to know the command.
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Jul 6, 2009
When a user logs into my webmail application, it creates entries in a table on MySQL called "identities" which works great however once the user is deleted fro Linux with the "userdel -r" command, the data still sits in MySQL. My question is how I can I remove the table data from old users? It appears as show below:
[code].....
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Mar 4, 2011
i want to generate random number in c programming from -1 to 1
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Jul 5, 2011
If this is correct [URL] I can expect that it will take more then 16 days to fill my 2TB partition from /dev/urandom. That's not workable for me. dd if=/dev/urandom of=/dev/sdxx has been running for 36 hours, and I need to finish setting up the filesystem. But I also need to make a "professional effort" at encrypting the partition. Ok, so I can try
Code: sudo /sbin/badblocks -c 10240 -s -w -t random -v /dev/sdxx So, what is "10240" doing there? Yes, I rtfm, "is the number of blocks which are tested at a time", but is that for the partition size? If so, then I would want to increase it to 204800 for a 2TB partition, right? If not, what should I do?
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Feb 18, 2010
I have tried a few packages but cannot find an easy intuitive interface for editing tables in a mySQL database. I just need to simply edit the table field data, import and export multiple rows, and filter the table data so only the rows are returned based on a string that I search for. The tables I edit have several thousand rows and some up to 30,000. I do not know how to write queries and it seems all these packages require that you know how to write sql queries to do what I need to do. On the mac I used Sequel Pro, which is dead easy to use and is mostly point and click to do all the above. Since my mySQL experience is very limited, I really need something simple like this.
I have tried:
MySQL Workbench
Navicat (lite version)
MySQL Query Browser
how to do what I need to do with the above packages.
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Aug 10, 2010
I already have my laptop as a server using a LAMP server + proftpd and the FTP->MySQL link up. I built myself a new Headless and set up the SSH and VNC on it and all that good jazz. LAMP works and everything. Proftpd+MySQL (using the proftpd-mod-mysql package from repo) doesn't seem to work on this headless box. So I used the tutorial from [URL]... Thinking "I'm using 10.04 - it's close enough". Both came up with the same error. 421 Service not available when I ftp from the localhost. Is their something I'm missing? the Laptop set up (also 10.04) works groovy fine. Also all the log files are blank.
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