An example of shell script.
This will print numbers 0 to 500 in one line.

#!/bin/bash
Z=0
LIMIT=500
while [ "$Z" -lt "$LIMIT" ]

do
echo -n "$Z... "
Z=$( expr $Z + 1 )
done
echo
exit 0

_____

ping the address received from positional parameter

#!/bin/bash

if [ $# -eq 0 ]
then
SITE="google.com"
else
SITE="$1"
fi

ping -c 2 $SITE > /dev/null
if [ $? != 0 ]
then
echo $(date +%F) ... Network Failure!
fi

_____

Here is the script that will loop two thousand times and print the statement on the screen.

#!/bin/sh

MAX=2000
i=1
echo " truncate table t1; "

while [ $i -le $MAX ]
do
echo " insert into t1(f1) values($i); "
i=`expr $i + 1`
done

The match operator is the tilde “~” which will match an expression in a record or field. In this example awk is used to search for a field, number 7, that matches “nologin”.

awk -F: '$7 ~ /nologin/' /etc/passwd
bin:x:1:1:bin:/bin:/sbin/nologin
daemon:x:2:2:daemon:/sbin:/sbin/nologin
adm:x:3:4:adm:/var/adm:/sbin/nologin

You can create a trigger to insert NULL values whenever a blank is found.

create trigger test1
before insert
on hvi
for each row
begin
if new.`Amt` = ' ' then
set new.`Amt` = null;
end if;
end;

yum install php-mysql

Is this ok [y/N]: y
Downloading Packages:
warning: rpmts_HdrFromFdno: Header V3 DSA signature: NOKEY, key ID 37017186

Public key for php-pdo-5.1.6-27.el5.x86_64.rpm is not installed
_____

Enable the RHEL network connection and disable GPG check.

vi /etc/yum.repos.d/rhel.repo
[base]
name=RHEL 5 $releasever - $basearch - Base
baseurl=http://10.10.10.1/yum/rhel/5/base/
enabled=1
gpgcheck=0

# /etc/init.d/mysqld start

Initializing MySQL database: Neither host 'localhost' nor 'localhost' could be looked up with /usr/bin/resolveip
Please configure the 'hostname' command to return a correct hostname.
[FAILED]

When you see such error message, you have to add hostname in /etc/hosts

Here is the code to show the files from the current directory.

<?php
if ($handle = opendir('.')) {
while (false !== ($file = readdir($handle)))
{
if ($file != "." && $file != "..")
{
$thelist .= '<a href="'.$file.'">'.$file.'</a> <p> ';
}
}
closedir($handle);
}
?>
<P>List of files:</p>
<P><?=$thelist?></p>


#!/bin/sh
for i in `find /var/lib/mysql/test/ -name "Table1.*"`
do
cp $i `dirname $i`'/test'`basename $i`
done

# duplicate a table Table1 by coping the files if it is a MyISAM table.

all the following words are actually MySQL keywords and should not be used as table/ column names.

timestamp, date, localtime, primary, repeat, schema

There are times when you do not notice any issue with it but at a later stage, one has to face a lot of issues because of this.

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.