jackie-do

• Get the max current value of a field (base on current data)

SELECT MAX(<field_name>) FROM <table_name>;

example:

SELECT MAX(id) FROM blogs;

jackie-do

Changing a file/directory ownership

1. Check file's permissions and ownership

ll

2. Changing A File Ownership

sudo chown : 

jackie-do

1. Create a linux user and set password

sudo adduser read_access

.. then enter your password for this user

2. Limit permission for the user (option) .. normally, this user only has root permission on it's directory. (/home/read_access)

3. Set read-only role for this user to use Postgresql

kieetnvt

I. INTRO
- Only valids for TEST env
- All cards below have expiration dates and security codes:
| Expiration Date | CVV2 / CVC3 | CID (American Express) |
| 08/2018         | 737         | 7373                   |
| 10/2020         | 737         | 7373                   |

II. CARDS
= Mastercard
| Card Number         | Card Type | Issuing Country |

kieetnvt

Config chung

Initializer

- Để các code khởi tạo trong thư mục config/initializers. Các đoạn code để trong thư mục này sẽ tự động execute khi server khởi động.
- Để các code khởi tạo thành các file riêng theo gem. Ví dụ: carrierwave.rb, devise.rb…

Global variable

- Các biến global như email dùng để gửi mail, hostname, … nên để trong các file config/enviroments/development.rb,config/enviroments/production.rb

kieetnvt

Optimize webpage speed:
- Tools: Google Pagespeed Insight, Gtmetrix.com, Webpagetest.org, Image Analysis of Webpagetest.org
- Tools mobile: Webpagetest.org, https://testmysite.thinkwithgoogle.com/

1. Using sprite CSS for all images

2. Optimize images using tool Tinypng.com

3. Eliminate render-blocking JavaScript in above-the-fold content
- Use content_for custom js in Rails