#1st Database Use. Help ?

41 messages · Page 1 of 1 (latest)

strong thorn
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Hello. I'm using Ubuntu and need to implement a school system with Java.
Idk what I have to do : Springboot?
Which database I use ? MySQL ?
I have MySql inside my computer but don't know how to launch a localhost. Pls someone help me. It's a very simple program.

terse wingBOT
#

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TIP: Narrow down your issue to simple and precise questions to maximize the chance that others will reply in here.

deep owl
#

Can you show your existing code?

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and what do you mean with launching a localhost?

cosmic hazel
#

These sound like questions that are better suited for your instructor.

strong thorn
strong thorn
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I only created the classes and rn i'm studying springboot

# 
import java.util.ArrayList;

public class Student {
    private String name; // 1o nome do aluno

    private ArrayList<Test> tests = new ArrayList<Test>();

    public Student(String name){
        this.name=name;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public void addTest(int grade){
        Test newTest = new Test(grade);
        tests.add(newTest);
    }

    public int getLowestGrade(){
        int lowest = 0;
        for (Test test : tests) {
            if (lowest > test.getGrade()) {
                lowest = test.getGrade();
            }
        }
        return lowest;
    }

    public int getHighestGrade(){
        int highest = tests.indexOf(0);
        for (Test test : tests) {
            if (highest < test.getGrade()) {
                highest = test.getGrade();
            }
        }
        return highest;
    }
    public double testsMean(){
        double sum = 0;

        for (Test test : tests){
            sum += test.getGrade();
        }

        double mean = sum/(tests.size());

        return mean;
    }
}
#

Student class above this message

# 
import java.util.ArrayList;

public class System {
    ArrayList<Student> students;

    public System(){
        students = null;
    }

    public void addStudent(String name){
        Student newStudent = new Student(name);
        students.add(newStudent);
    }
}
#

System class

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class Test {
    private int grade;

    public Test(int grade) {
        this.grade = grade;
    }

    public int getGrade() {
        return grade;
    }
}```
#

Test class

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My system have to show the following options to the user:

Register student
List students
See biggest note.

E. Exit

If I choose the 2st option, the output will be something like this :
Carl
Jean
Peter

B. Back
E. Exit

If I choose 2 ( Jean ), I will have this :
Student : Jean
Tests Mean : 0
Biggest note : 0
Lower note : 0
Done tests : 0

Register test for this student

B. Back
E. Exit

If I choose 1 In order to register test, I have to ask the user the test note and register it .

#

I need to implement the main and after that start syncing with my db

deep owl
#

so you have a Spring Boot application and you want to save these objects to the DB?

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Can you show your pom.xml (or build.gradle)?

strong thorn
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<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>3.0.4</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.api</groupId>
    <artifactId>systemVidenci</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>systemVidenci</name>
    <description>Demo project for Spring Boot</description>
    <properties>
        <java.version>19</java.version>
    </properties>
    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-data-jpa</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-validation</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>

        <dependency>
            <groupId>org.postgresql</groupId>
            <artifactId>postgresql</artifactId>
            <scope>runtime</scope>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>

</project>
deep owl
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ok do you have the database connection properties in your application.properties file already?

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So, Spring Boot doesn't know you are using MySQL

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If you want to connect to a MySQL DB from Spring, you first need to add the MySQL JDBC driver (MySQL Connector/J) to the pom.xml

strong thorn
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So I have to generate a new pom xml from Spring initializer ?

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I only found postgre sql

deep owl
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no, you can add it to your existing pom.xml

# 
<dependency>
    <groupId>com.mysql</groupId>
    <artifactId>mysql-connector-j</artifactId>
</dependency>
# 
<dependency>
    <groupId>com.mysql</groupId>
    <artifactId>mysql-connector-j</artifactId>
</dependency>
#

After doing that, can you show your application.properties?

strong thorn
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My app properties is empty

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I didn't created the db already

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server.port = 8090

spring.datasource.url=jdbc:mysql://localhost/api_spring?useTimezone=true&serverTimezone=UTC
spring.datasource.username=root
spring.datasource.password=senha
spring.datasource.driver-class-name=com.mysql.cj.jdbc.Driver

spring.jpa.hibernate.ddl-auto=update

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I got this app properties

deep owl
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yes

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this is what's needed for MySQL

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Now, you need to tell spring what classes you want to persist

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in your case, you want to persist instances of the student class

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So you need to mark your student class

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For doing that, add @Entity to it which tells Spring that Student objects might be persiszed in the DB

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each element of a table needs to have a (unique) primary key

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What do you want to choose for that? A new field?