# Java Spring boot& DB new
###### Day1:
* learn Sprnig boot for beginners
<!-- [1. Video coures from YT](https://www.youtube.com/watch?v=HTuE0GZtnM4) -->
* Setup SpringBoot ( JAVA ) ---IntelliJ IDEA
1. New Project select Spring Assistant.
2. Select Web click Spring Web.
3. Select Template Engines click Thymeleaf
4. Select Developer Tools click Spring BootDevTools
## Strat bulid Spring boot using Java code --mavnen
#### 1. Create Application
@SpringBootApplication
public class DemoApplication {
public static void main(String[] args) {
SpringApplication.run(DemoApplication.class, args);
}
}
___
#### 2. Create index.html to templates file
skip...
<body>
<h3>Hello Spring boot</h3>
<a href="/hello">Click here</a>
</body>
</html>
#### 3. Create hello.html to templates file
skip....
<body>
<h3>Hello Spring boot</h3>
</body>
#### 4. Create(a Spring MVC controller with Thymeleaf template) WebController ( because didn't crate this .java the index page can't find other .html)
skip....
@Controller
public class WebController {
@RequestMapping("/hello")
public String sayHello(){
System.out.println("Say hello world spring boot");
return "hello";
}
}
___
change to
WebController.java
@Controller
public class WebController {
@RequestMapping("/hello")
public String sayHello(Model model){
System.out.println("Say hello world spring boot");
model.addAttribute("message","Greetings how");
return "hello";
}
}
---
hello.html
<!DOCTYPE html>
<html lang="en" xmlns:th="http://www.thymeleaf.org">
<head>
<meta charset="UTF-8">
<title>Hello Page</title>
</head>
<body>
<h3>Hello Spring boot from Intellij IDEA</h3>
<h2 th:text="${message}"></h2>
</body>
</html>
#### 5. look test flie try JUnit test
@SpringBootTest
class DemoApplicationTests {
@Autowired
private WebController controller;
@Test
void contextLoads() {
Assertions.assertThat(controller).isNotNull();
}
}
#### 6. Create(REST controller) WebServicesController using @RestController
@RestController
public class WebServicesController {
@GetMapping("/rest")
public String sayREST(){
return "Great, Let's take a REST with Spring boot";
}
}
and add to hello.html
<a href="/rest">Take a REST</a>
#### 7. Package & Run application
1.Open Maven on right side
2.Tap mvn package
#### 8. Create
## More information
* MVC
1. Model
2. View
3. Controller
# Issues
##### After start Appaction will started and stop.
Can open pom.xml file
Add command line:
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
## Databases
* Data type:
1. CHAR / VARCHAR / TEXT
2. INTEGER / DECIMAL(10,2)
3. DATE / DATETIME
4. BLOB = Binary Large Object
* DML (Data Manipulation Language)資料操作語言
1. insert
2. delete
3. update
* DQL (Data Query Language) 資料查詢語言
1. select
* Simple to use
1. Create database 'NAME';
2. Show databases;
3. Create table;
4. Show tables;
5. Drop database 'NAME';
* Create table
###### tags: need to use ` 在 1 旁邊
create table `awesomdb`.`heroes` (
`id` int not null auto_increment,
`name` varchar(100) not null,
`gener` char(1) null,
`age` int null,
`hero_level` char(1) not null,
`hero_rank` int null,
`description` text null,
PRIMARY KEY(`id`));
* 新增欄位
(在 descriotion 後面新增)
alter table `awesomdb`.`heroes`
-> add column `abc` varchar(45) null after `description`;
* 移除欄位
alter table `awesomdb`.`heroes`
drop column `abc`;
* 寫入資料
insert into awesomedb.heroes
(name,age,hero_level,hero_rank, description)
values("KK", 18,"S",1,"hi");
* 查詢資料
select * from heroes; (會把全部資料撈出來)
select * (把指定的 資料撈出來)
from heroes
where hero_level = 's' and gender = 'F';
select name, gender(部分欄位)
from heroes
where hero_level = 's' and gender = 'F';
(查詢沒有填寫的)
select *(部分欄位)
from heroes
where age is null;
(查詢有指定文字的關鍵字)
select *(部分欄位)
from heroes
where name like '%查詢的字%';
(or)
where name like '查詢的字%';在最前面
where name like '%查詢的字';在最後面
(查詢年紀 10~25)
where age >= 10 and age <= 25
(or)
where age between 10 and 25
(查詢 hero level 's' 跟 'a' 級的)
select name,age,hero_level from heroes
where hero_level = 'S' or hero_level = 'A';
(or)
where hero_level in ('S' ,'A');
(查詢 不是 's' 的人) <> 是不等於
select name,age,hero_level from heroes
where hero_level <> 'S' and hero_level <> 'A';
or
where hero_level not in ('S','A')
* 更新資料
UPDATE `awesome_db`.`heroes` SET `age` = '11' WHERE (`id` = '5');
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