DB

CRUD

 

Create

Read

Update

Delete

 

DB: 계층형, 관계형, 객체형, 객체 관계형 존재

 

SQL

 

JDBC: 자바 코드에서 SQL문을 작성하여 코드를 작성

 

ORM(Object Relational Mapping): 자동으로 자바 코드가 SQL문으로 변경하게 만드는 기술

-> Hibernate, JPA

 

MySqld 초기화

 

Mysqld 실행

 

 

Mysql 실행 -> 패스워드 입력

 

패스워드 변경

 

 

초기화 후 패스워드는 C:\mysql-8.0.30-winx64\data의 err로 끝나는 파일에 있음

 

DB자바로 실행

        String dbUser="root";

        String dbPassword="PW";

        String dbUrl="jdbc:mysql://localhost:3306/ooo";

                        //mysql     서버IP: 서버Port / DB 이름

 

DB 연결

       Connection conn = DriverManager.getConnection(dbUrl, dbUser, dbPassword);

 

 

public class MysqlConn {

    public void dbconn(){

        String dbUser = "root";

        String dbPassword = "PW";

        String dbUrl = "jdbc:mysql://localhost:3306/ooo";

                         //mysql :// 서버IP : 서버Port / DB 이름

        Connection conn = null;

        Statement stmt=null;

        ResultSet rs=null;

        try {

            Class.forName("com.mysql.cj.jdbc.Driver");

            conn = DriverManager.getConnection(dbUrl, dbUser,dbPassword);

            stmt=conn.createStatement();

            rs=stmt.executeQuery("Select 1");

            if(rs.next()){

                int num=rs.getInt(1);

                System.out.println(num);

            }

            // SQL 쿼리문 실행

        } catch (Exception e) {

            throw new RuntimeException(e);

        }

    }

}

 

 

dbconn test

class ConnTestThread extends Thread{

    public void run() {

        MysqlConn mysqlConn = new MysqlConn();

        mysqlConn.dbconn();

    }

}

public class ConnTest {

    public static void main(String[] args) {

        for(int i=0;i<10;i++){

            Runnable r = new ConnTestThread();

            Thread t = new Thread(r);

            t.start();

        }

    }

}

 

 

 

Hikari

import java.sql.Connection;

import java.sql.PreparedStatement;

import java.sql.ResultSet;

import com.zaxxer.hikari.HikariConfig;

import com.zaxxer.hikari.HikariDataSource;

public class HikariCPEx {

    public void dbconn() {

        String configFile = "src/main/resources/db.properties";

        HikariConfig cfg = new HikariConfig(configFile);

        HikariDataSource ds = new HikariDataSource(cfg);

        Connection conn = null;

        PreparedStatement pst = null;

        ResultSet rs= null;

        try{

            conn = ds.getConnection();

            pst=conn.prepareStatement("SELECT 10000");

            rs=pst.executeQuery();

            while(rs.next()){

                System.out.println(rs.getInt(1));

            }

        }catch(Exception e){

        }

    }

}

 

Hikari test

class HikariConnTestThread extends Thread{

    public void run() {

        HikariCPEx hikariCPEx = new HikariCPEx();

        hikariCPEx.dbconn();

    }

}

public class ConnTest {

    public static void main(String[] args) {

        for(int i=0;i<10;i++){

            Runnable r = new HikariConnTestThread();

            Thread t = new Thread(r);

            t.start();

        }

    }

}