There are 4 checks need to be performed while creating foreign keys.

1) Check if you are using InnoDB table type for both the tables.
2) Make sure that both the columns are indexed.
3) Make sure that the constraint name for e.g. "FK_batch_relation" is not used anywhere else. Or better, change the name to something else.
4) Make sure that the column type matches. For e.g. If one is INT then the parent column can not be varchar.

Downloaded rpms from mysql.org

rpm -ivh MySQL-client-community-5.1.52-1.rhel5.x86_64.rpm MySQL-server-community-5.1.52-1.rhel5.x86_64.rpm

If you want to uninstall just give rpm –e package name.

You can use "live bookmarks", the built-in RSS reader of Firefox to read private feeds.
To view Gmail messages in this manner, just subscribe to a new feed, enter https://mail.google.com/mail/feed/atom in the URL field, and submit your Gmail address and password.

https://addons.mozilla.org/en-us/firefox/addon/wikisearch-concise/

The user will select any word from the current webpage and choose "wikipedia Concise" on the right click. The selection will be submitted to the website mobile.wikipedia.org
For e.g. if I have selected the word "obama" and searched using "wikipedia description", I will be directed to the site that will show me a few lines about Barack Obama.

The URL is menioned in the url tag and that looks something like this.
mobile.wikipedia.org/transcode.php?go=obama

pretty easy, huh?

innodb_flush_method=O_DIRECT
innodb_file_per_table
innodb-flush-log-at-trx-commit = 2

# number of cpus * number of disks * 2
#innodb_thread_concurrency=16
_____
Lowering the value of swappiness may help mysql

# default 60
echo '50' > /proc/sys/vm/swappiness

Make the change permanent:
/etc/sysctrl.conf
vm.swappiness = 50

# innodb basic settings
innodb_buffer_pool_size=1G
innodb_log_file_size=512M

# MyISAM only cnf setting
user=root
skip-innodb
default-storage-engine=myisam
bulk_insert_buffer_size=1G
key-buffer=1G

# increase default 2 GB on 32 bit OS
myisam_max_sort_file_size=40G
myisam_sort_buffer_size=512M

# make sure temp directory has sufficient space
# and mysql has permission to write
tmpdir=/

Brace expansion is used to generate arbitrary strings. For e.g.
ls mysql*.0000{1..3}

will list the files like mysql.00001 mysql.00002 & mysql.00003

This can also be used for something like this...

cp mysql.log{,.bak}
>> cp mysql.log mysql.log.bak

cp $da.log{.bak,}
>> cp 2010-05-28.log.bak 2010-05-28.log

Microsoft mess is not a topic for me to blog anymore. But since someone whose blog I track has mentioned about it, let me link the article.

http://ma.tt/2010/06/windows-reboot/

The only advice is do not use Micro$oft products when better alternatives are available. The machine automatically boots when the security updates are installed silently! Another reason to use pirated software?

Instead of specifying password in mysql command line, I prefer storing it in ~/.my.cnf while doing such works to avoid typing passwords every time. you can create this file or supply password as you wish.

$ cat ~/.my.cnf
[client]
user=root
password="password"

You can save the current file as a new file after making changes,
:w new_file.txt

If you want only 50 lines starting from line number 100, use...
:100,150w! new_file.txt

#!/bin/sh
unset REPLY
until [[ $REPLY ]]; do read -p "Enter your name: "
done
echo "welcome $REPLY"