soyoes

select * 
NOT IN
!=	//index失効
<>	//index失効
is null	//index失効, 方法:NOT NULL, default=0, where xxx=0
where OR //index失効失効 
	改善前: 
	select id from t where num=10 or num=20
    改善後:
    select id from t where num=10

soyoes

* strong, weak, assign
http://stackoverflow.com/questions/8927727/objective-c-arc-strong-vs-retain-and-weak-vs-assign

* bridge (void* => id, id => void*)
http://stackoverflow.com/questions/18976016/how-to-specify-property-to-c-pointer-in-arc-environment

* arr.indexOf
```Objective-C
//BAD: it returns max int.
(int)[arr indexOfObject:obj]>0

soyoes

1: keychain->[Keychain access]->[Certificates Assistants]->[Request ...]->{email:YOURs, Common Name:"APP_NAME PUSH"}->[save to disk] (f1.certSigningRequest)
  * DON'T forget to set [Common Name]="APP_NAME PUSH", or you won't find it later
  * DON'T through away f1.certSigningRequest, it can be used while renew a year later.
2: dev center->certificates->[Identifiers]->App IDs-> [+] button
   -> check enable Push -> [Create Certificate...] -> [continue] -> upload the file of #1 (f1.certSigningRequest) -> [Generate] -> [Download] => you got a "aps_development.cer" file (f2.cer)
  * DON'T forget to install f2.cer by double click!
3: keychain->certificates->[your app buldle id]->right click->export ... ->save as f3.p12
  * YOU may have to specify a password of at least 4 bit !
4: make PEM file with your f3.p12, u will get cert.pem (a cert pem file)
```Bash

soyoes

https://faces.fiverr.com
http://urban-walks.com/
http://gameit.us/
https://www.quizup.com/en

soyoes

$pattern = '/foo(?=bar)/';

preg_match($pattern,'Hello foo'); // BAD
preg_match($pattern,'Hello foobar'); // OK

soyoes

Flex box display

element with flex/inline-flex affects its child nodes!

Vertical or horizontal layout child nodes

{display:flex; flex-direction:row;} /*horizontal*/
{display:flex; flex-direction:column;} /*vertical*/

soyoes

<?php
trait DynamicDefinition {
    
    public function __call($name, $args) {
        if (is_callable($this->$name)) {
            return call_user_func($this->$name, $args);
        }
        else {
            throw new \RuntimeException("Method {$name} does not exist");
        }