The mysql general logs use the following date format to display current date.

date '+%y%m%d %H:%M:%S'

The same can be used in the shell script to echo date at the beginning of the line.

If you want someone to access all the files and locations that mysql has access to, then add the username to the mysql group.

vi /etc/group

mysql:x:27:santosh

init_connect can be used to disable foreign key checks.
mysql> SET GLOBAL init_connect='SET foreign_key_checks = 0';

As well something similar for the GLOBAL options my.cnf file.
init_connect='SET foreign_key_checks = 0';

The super user will bypass the init-connect directives. So the user without the super privilege can take benefit of this setting.

Here is the list error codes mysql will return when it fails to connect to the mysql instance.

101 error: Can not connect to MySQL server (101)
102 error: '(proxy) all backends are down'
103 error: 'Access denied for user 'user'@'10.10.10.10' (using password: NO)'
104 error: 'Access denied for user 'user'@'10.10.10.10' (using password: YES)'
105 error: 'Host '10.10.10.10' is not allowed to connect to this MySQL server'
111 error: 'Lost connection to MySQL server at 'reading initial communication packet', system error: 111'
113 error: 'Lost connection to MySQL server at 'reading initial communication packet', system error: 113'
114 error: Unknown MySQL server host (3)

660 mysql data dir
700 home directory
777 world writeable files
chmod +x asper.sh OR (chmod 754 asper.sh)

Default value of kernel net.ipv4.tcp_max_syn_backlog is 2048, increase it to 8192. Default value of net.core.somaxconn kernel setting is 128 and can be increased to 1000
MySQL parameter back_log which has default value of just 50. You may want to set it to 1000 or even higher.

If innodb_fast_shutdown is set to 0, the log files are purged when mysqld shuts down - larger files mean a longer shutdown time. The default for innodb_fast_shutdown is 1, which
means that the log files are not purged before a shutdown. A value is 2 simulates a crash, and at the next startup InnoDB will do a crash recovery.
This can be useful when testing to see approximately how long InnoDB takes to recover from a crash, to determine if the size of your log files is too large.

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