MySQL: CAST example 
SELECT 
CAST(CASE eoy
WHEN 0 THEN 'No Voted'
ELSE category/* Keep Original Value*/
END as CHAR) AS Result
FROM `vote_email`


//see all
SELECT eoy FROM vote_email


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MySQL: Case Expression vs Case Statement 
The CASE expression evaluates to a value, i.e. it is used to evaluate to one of a set of results, based on some condition.
Example:

SELECT CASE
WHEN type = 1 THEN 'foo'
WHEN type = 2 THEN 'bar'
ELSE 'baz'
END AS name_for_numeric_type
FROM sometable`


The CASE statement executes one of a set of statements, based on some condition.
Example:

CASE
WHEN action = 'update' THEN
UPDATE sometable SET column = value WHERE condition;
WHEN action = 'create' THEN
INSERT INTO sometable (column) VALUES (value);
END CASE


You see how they are similar, but the statement does not evaluate to a value and can be used on its own, while the expression needs to be a part of an expression, e.g. a query or an assignment. You cannot use the statement in a query, since a query cannot contain statements, only expressions that need to evaluate to something (the query itself is a statement, in a way), e.g. SELECT CASE WHEN condition THEN UPDATE table SET something; END CASE makes no sense.

http://stackoverflow.com/questions/1243 ... -statement

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MySQL: User Management 
// view all users
SELECT user,host FROM mysql.user;

//drop a user
DROP USER 'dev-webuser'@'localhost';

//create a user and assign password
GRANT ALL PRIVILEGES ON db_name.* TO 'webuser'@'localhost' IDENTIFIED BY 'secret123'

// disply logged in grants
SHOW GRANTS;



//
CREATE USER 'jeffrey'@'localhost' IDENTIFIED BY 'mypass';

//
GRANT SELECT,INSERT,UPDATE,DELETE ON my_db.* TO 'michael'@'localhost';

//
GRANT ALL ON my_db.* TO 'michael'@'localhost';

//
GRANT ALL ON my_db.* TO 'my_user'@localhost IDENTIFIED BY 'my_pass';


//update user's password:
SET PASSWORD FOR 'webuser'@'localhost' = PASSWORD('dev123');

// MySQL 8 :
root@5f288b2166ba:/# mysql -p
...
mysql>
mysql> CREATE USER 'coolUser'@'%' IDENTIFIED WITH mysql_native_password BY 'YYYYYY';
Query OK, 0 rows affected (0.01 sec)

mysql>
mysql> grant all on *.* to 'coolUser'@'%';
Query OK, 0 rows affected (0.01 sec)

#Starting with MySQL 8 you no longer can (implicitly) create a user using the GRANT command. Use CREATE USER instead, followed by the GRANT statement:
mysql> CREATE USER 'root'@'%' IDENTIFIED BY 'PASSWORD';
mysql> GRANT ALL PRIVILEGES ON *.* TO 'root'@'%' WITH GRANT OPTION;
mysql> FLUSH PRIVILEGES;


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RPM Basic Tasks 
//package info
rpm -qi "package"

//Listing all installed packages
rpm -qa

//remove a package
rpm -e "package"
rpm -e "package" "package" //dependencies

// install a package
rpm -Uvh package_file.rpm

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Basic Tasks: memcached 
[acool@acool ~]$ telnet localhost 11211
Trying ::1...
Connected to localhost.
Escape character is '^]'.
stats
...
stats slabs
...
stats items
...
stats cachedump 15 0
ITEM memc.sess.key.tb7mgf58nb0pnn7ag840q5r5k6 [1875 b; 1467144640 s]
ITEM memc.sess.key.9nt5nrcptemi2m0d9g3k95vl76 [1911 b; 1467144640 s]
ITEM memc.sess.key.5k8d2qpko4lg4rn6fue1ces0j6 [230 b; 1467144640 s]
...
get memc.sess.key.5k8d2qpko4lg4rn6fue1ces0j6
...
delete memc.sess.key.5k8d2qpko4lg4rn6fue1ces0j6
DELETED

set MyJson 0 100 16
{"name":"angel"}
STORED

flush_all
OK

quit
[acool@acool ~]$



Also see memcached-tool utility.


//flush memcached
echo 'flush_all' | nc localhost 11211//or:
echo 'flush_all' | netcat localhost 11211


/*****Telnet Examples******/

//connect to memcached
telnet localhost 11211

//storing data in memcached server, syntax: set KEY META_DATA EXPIRY_TIME LENGTH_IN_BYTES
(LENGHT_IN_BYTES must match content!!!)
set Test 0 100 16
Angel is Testing

//retrieve data
get Test

//getting stats
stats

//stats shortcut
[webmaster@dev ~]$ echo stats | nc localhost 11211

/*****PHP Examples******/
Coming.... hoping sooner rather than later ...but coming, for sure coming.

10/4/2013 ...there:
http://angelcool.net/sphpblog/comments. ... 004-174818

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Basic Tasks with: rsync & scp  
//scp copy a remote file to local machine
scp username[at]10-network.com:~/html/3.gif .

//copy a remote directory to local machine
scp -r username[at]10-network.com:~/html .


//rsync uses ssh by default since version 2.6 (2004)

//rsync over ssh using port 222
rsync -v --rsh='ssh -p222' user[at]example.10-network.net:~/image.jpg .
//...or:
rsync -v -e 'ssh -p222' user[at]example.10-network.net:~/image.jpg .


//OK
rsync -avhe 'ssh -p22' --progress payless[at]paylesstosell.net:~/html/* .

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Counting Table Columns 
SELECT COUNT(*)
FROM INFORMATION_SCHEMA.COLUMNS
WHERE table_schema = 'database_name'
AND table_name = 'table_name'

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Adding DNS Servers in CentoOS 
!!!!CentOS 6.4 !!!!

//the following command overwrites /etc/resolv.conf (or when rebooting)
service network restart
//instead, add the following to /etc/sysconfig/network-scripts/ifcfg-eth0
DNS1=4.2.2.2
DNS2=4.2.2.1

!!!!!!!!!!!!!!!!!!!


//open this file
vim /etc/resolv.conf

//add entries
nameserver 4.2.2.2
nameserver 4.2.2.1

//test
nslookup barney.com

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How to configure network interfaces in CentOS (static ip) 
//edit interface configuration file
sudo vim /etc/sysconfig/network-scripts/ifcfg-eth0

//set settings
DEVICE=eth0
BOOTPROTO=none
HWADDR=00:05:29:E0:4F:3D
IPADDR=10.0.1.10
NETMASK=255.255.255.0
GATEWAY=10.0.1.1
DNS1=4.2.2.2
DNS2=4.2.2.1
ONBOOT=yes
TYPE=Ethernet


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IPTABLES common tasks 
//list rules
iptables -L --line-numbers
iptables --list

//inserting rules
iptables -I INPUT -p tcp --dport 80 -j ACCEPT //inserts a rule on top
iptables -I INPUT 5 -p tcp --dport 21 -j ACCEPT //inserts a rule on the 5th position

//deleting rules by line number
iptables -D INPUT 5 //deletes the 5th rule

//saving rules
service iptables save //centos



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