Ciao ragazzi,
ho installato sul mio pc MySQL Workbench ed Eclipse con Java SE.
Vorrei realizzare un database e poi, successivamente, andare a creare le tabelle, i campi e tutto il resto... Ma incontro delle difficoltà che non riesco a comprendere.
In rete ho trovato un esempio per creare un database con MySQL:
Poi ho inserito, tramite il path del progetto, il Jar esterno (JBDC Connector: mysql-connector-java preso dentro un file zip scaricato dal sito MySQL).codice://STEP 1. Import required packages import java.sql.*; public class JDBCExample { // JDBC driver name and database URL static final String JDBC_DRIVER = "com.mysql.jdbc.Driver"; static final String DB_URL = "jdbc:mysql://localhost/"; // Database credentials static final String USER = "username"; static final String PASS = "password"; public static void main(String[] args) { Connection conn = null; Statement stmt = null; try{ //STEP 2: Register JDBC driver Class.forName("com.mysql.jdbc.Driver"); //STEP 3: Open a connection System.out.println("Connecting to database..."); conn = DriverManager.getConnection(DB_URL, USER, PASS); //STEP 4: Execute a query System.out.println("Creating database..."); stmt = conn.createStatement(); String sql = "CREATE DATABASE STUDENTS"; stmt.executeUpdate(sql); System.out.println("Database created successfully..."); }catch(SQLException se){ //Handle errors for JDBC se.printStackTrace(); }catch(Exception e){ //Handle errors for Class.forName e.printStackTrace(); }finally{ //finally block used to close resources try{ if(stmt!=null) stmt.close(); }catch(SQLException se2){ }// nothing we can do try{ if(conn!=null) conn.close(); }catch(SQLException se){ se.printStackTrace(); }//end finally try }//end try System.out.println("Goodbye!"); }//end main }//end JDBCExample
Ora lancio il programma e vedo questo errore:
Perchè incontro questi strani problemi?codice:Connecting to database... com.mysql.jdbc.CommunicationsException: Communications link failure due to underlying exception: ** BEGIN NESTED EXCEPTION ** java.net.ConnectException MESSAGE: Connection refused: connect STACKTRACE: java.net.ConnectException: Connection refused: connect at java.net.DualStackPlainSocketImpl.connect0(Native Method) at java.net.DualStackPlainSocketImpl.socketConnect(Unknown Source) at java.net.AbstractPlainSocketImpl.doConnect(Unknown Source) at java.net.AbstractPlainSocketImpl.connectToAddress(Unknown Source) at java.net.AbstractPlainSocketImpl.connect(Unknown Source) at java.net.PlainSocketImpl.connect(Unknown Source) at java.net.SocksSocketImpl.connect(Unknown Source) at java.net.Socket.connect(Unknown Source) at java.net.Socket.connect(Unknown Source) at java.net.Socket.<init>(Unknown Source) at java.net.Socket.<init>(Unknown Source) at com.mysql.jdbc.StandardSocketFactory.connect(StandardSocketFactory.java:256) at com.mysql.jdbc.MysqlIO.<init>(MysqlIO.java:271) at com.mysql.jdbc.Connection.createNewIO(Connection.java:2771) at com.mysql.jdbc.Connection.<init>(Connection.java:1555) at com.mysql.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:285) at java.sql.DriverManager.getConnection(Unknown Source) at java.sql.DriverManager.getConnection(Unknown Source) at JDBCExample.main(JDBCExample.java:22) ** END NESTED EXCEPTION ** Last packet sent to the server was 1 ms ago. Goodbye! at com.mysql.jdbc.Connection.createNewIO(Connection.java:2847) at com.mysql.jdbc.Connection.<init>(Connection.java:1555) at com.mysql.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:285) at java.sql.DriverManager.getConnection(Unknown Source) at java.sql.DriverManager.getConnection(Unknown Source) at JDBCExample.main(JDBCExample.java:22)

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