Node JS tutorial for beginner

Question: What is NodeJS
Node.js is a platform built for fast and scalable network applications. It uses an event-driven, non-blocking I/O model that makes it lightweight and efficient, perfect for data-intensive real-time applications that run across distributed devices. It can be used in Websites application, Android applicationa and IOS application etc.


Question: What type of framework is Nodejs?
NodeJS is JavaScript-based framework/platform



Question: Is Nodejs Server OR Cient Side?
Both, Node work for both.



Question: What is REPL?
REPL stands for Read Eval Print Loop
Node.js comes with virtual environment called REPL (also Node shell).


Question: What are most common REPL Commands?

ctrl + c

Terminate the current command.

ctrl + c twice 

terminate the Node REPL.

Up/Down Keys

see command history.

tab Keys

list of current commands.

.help

list of all commands.

.break

exit from multiline expression.

.save filename 

save the current Node REPL session to a file.

.load filename

load file content in current Node REPL session.



Question: How to exist from REPL?

ctrl + c twice 

Question: How to install module in NodeJS?

npm install express

for install express.


Question: How to uninstall module in NodeJS?

npm uninstall express

for uninstall express.

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ThinkPHP SQL queries with examples

Question: How to create Model Object?

$userObj= D("Common/Users");

Question: How to add simple AND Query?

$map=array();
$userObj= D("Common/Users");
$map['user_type'] = 2;
$map['city_id'] = 10;
 $lists = $userObj
                ->alias("u")                
                ->where($map)
                ->order("u.id DESC")
                ->select();

Question: How to add simple OR Query?

$map=array();
$userObj= D("Common/Users");
$map['u.username|u.email'] = 'email@domain.com';  //username OR email is email@domain.com
 $lists = $userObj
                ->alias("u")                
                ->where($map)
                ->order("u.id DESC")
                ->select();

Question: How to use =, >, < in Query?

$map['id']  = array('eq',1000); //equal to 1000

$map['id']  = array('neq',1000); //Not equal to 1000

$map['id']  = array('gt',1000);//Greater than 1000

$map['id']  = array('egt',1000);//Greater than OR EQual 1000

$map['id']  = array('between','1,8'); //Between 1-8

Question: How to use like Query?

$map=array();
$userObj= D("Common/Users");
$map['name'] = array('like','test%'); //like test%
 $lists = $userObj
                ->alias("u")                
                ->where($map)
                ->order("u.id DESC")
                ->select();

Question: How to use like Query with NOT?

$map=array();
$userObj= D("Common/Users");
$map['b'] =array('notlike',array('%test%','%tp'),'AND'); //Not like %test% and %tp
 $lists = $userObj
                ->alias("u")                
                ->where($map)
                ->order("u.id DESC")
                ->select();

Question: How to use Inner JOIN ?

$map=array();
$userObj= D("Common/Users");
$map['name'] = array('like','test%'); //like test%
 $lists = $userObj
                ->alias("u") 
                ->join(C('DB_PREFIX') . "profile as p ON u.id = p.uid")               
                ->where($map)
                ->order("u.id DESC")
                ->select();

Question: How to use LEFT JOIN ?

$map=array();
$userObj= D("Common/Users");
$map['name'] = array('like','test%'); //like test%
 $lists = $userObj
                ->alias("u") 
                ->join('LEFT JOIN '.C('DB_PREFIX') . "profile as p ON u.id = p.uid")               
                ->where($map)
                ->order("u.id DESC")
                ->select();

Question: How to use RIGHT JOIN ?

$map=array();
$userObj= D("Common/Users");
$map['name'] = array('like','test%'); //like test%
 $lists = $userObj
                ->alias("u") 
                ->join('RIGHT JOIN '.C('DB_PREFIX') . "profile as p ON u.id = p.uid")               
                ->where($map)
                ->order("u.id DESC")
                ->select();

Question: How to use group by and having?

$map=array();
$userObj= D("Common/Users");
$map['name'] = array('like','test%'); //like test%
 $lists = $userObj
                ->alias("u") 
                ->join('RIGHT JOIN '.C('DB_PREFIX') . "profile as p ON u.id = p.uid")               
                ->where($map)
                ->order("u.id DESC")
                 ->group('u.id')                
                 ->having('count(p.id) >0')
                ->select();

Question: How to use count(for total records)?

$map=array();
$userObj= D("Common/Users");
$map['name'] = array('like','test%'); //like test%
 $count = $userObj
                ->alias("u")                 
                ->where($map)                
                ->count();

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