user table in mysql database
| user_id | Last Name | First Name |
|---|---|---|
| 1 | Bagshot | Bathilda |
| 2 | Black | Sirius |
| 3 | Brown | Lavender |
| 4 | Chang | Cho |
| 5 | Creevey | Colin |
| 6 | Crouch | Bartemius |
| 7 | Delacour | Fleur |
| 8 | Diggle | Dedalus |
| 9 | Diggory | Cedric |
| 10 | Dumbledore | Aberforth |
| 11 | Dumbledore | Albus |
| 12 | Dursley | Dudley |
| 13 | Dursley | Petunia |
| 14 | Dursley | Vernon |
| 15 | Filch | Argus |
| 16 | Finnigan | Seamus |
| 17 | Fletcher | Mundungus |
With a limit of 5 per page, we would expect the first and second page to look like: Page 1:
| user_id | Last Name | First Name |
|---|---|---|
| 1 | Bagshot | Bathilda |
| 2 | Black | Sirius |
| 3 | Brown | Lavender |
| 4 | Chang | Cho |
| 5 | Creevey | Colin |
Page 2:
| user_id | Last Name | First Name |
|---|---|---|
| 6 | Crouch | Bartemius |
| 7 | Delacour | Fleur |
| 8 | Diggle | Dedalus |
| 9 | Diggory | Cedric |
| 10 | Dumbledore | Aberforth |
create table User(
user_id INT NOT NULL AUTO_INCREMENT,
last_name VARCHAR(40) NOT NULL,
first_name VARCHAR(40) NOT NULL,
PRIMARY KEY ( user_id )
);INSERT INTO User (last_name,first_name)
VALUES ('Bagshot','Bathilda'),
('Black','Sirius'),
('Brown','Lavender'),
('Chang','Cho'),
('Creevey','Colin'),
('Crouch','Bartemius'),
('Delacour','Fleur'),
('Diggle','Dedalus'),
('Diggory','Cedric'),
('Dumbledore','Aberforth'),
('Dumbledore','Albus'),
('Dursley','Dudley'),
('Dursley','Petunia'),
('Dursley','Vernon'),
('Filch','Argus'),
('Finnigan','Seamus'),
('Fletcher','Mundungus');
URL: /user?limit=5
{
"data": [
{
"last_name" : "Bagshot",
"first_name" : "Bathilda",
}
],
"cursor": {
"previous_page": "/user?limit=5&before=cHJldl9fX0Nyb3VjaA==" ,
"next_page": "/user?limit=5&after= bmV4dF9fX0R1bWJsZWRvcmU="
}
}
base64的應用特別廣泛，個人在開發中遇到最多的兩個方面，第一個是URL的base64，另一個是圖片base64。
先說第一種，已經有urlencode了，為什麼還需要base64 的URL。各有用途。
urlencode是將-_. 之外的所有非字母數字字符都將被替換成百分號（%）後跟兩位十六進位數，空格則編碼為加號（+）。如果一個URL裡面有+ 有空格，是不是urlencode就搞不定，使用base64就會迎刃而解。帶來的代價就URL比原理長了1/3
圖片編碼的問題，經常跟客戶端開發的時候，客戶端使用二進位流上傳圖片的時候比較複雜，就可以使用base64將圖片的二進位編碼轉成base64，服務端接到數據之後再basedecode之後就是圖片的二進位流。特別方便，帶來的結果就是，傳輸的數據多了1/3。
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