Probleme avec sql

Bonjour,

Je viens de programmer une application pour creer une base de donnes sql, mais c'est toujours la meme erreur ".
com.mysql.jdbc.exceptions.MySQLSyntaxErrorException: Table 'etudiant' already exists"

voici mon code et merci pour votre temps :)

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;
import java.sql.Statement;

import javax.swing.ImageIcon;
import javax.swing.JOptionPane;


public class CreateBD {
static final String JDBC_DRIVER = "com.mysql.jdbc.Driver";
static final String DB_URL = "jdbc:mysql://localhost/";

static final String USER = "root";
static final String PASS = "";

public CreateBD()
{
JOptionPane jop1, jop3;
ImageIcon img = new ImageIcon("D:\\programmes android\\calculMoeyenneIia\\src\\info.PNG");
ImageIcon img2 = new ImageIcon("D:\\programmes android\\calculMoeyenneIia\\src\\error.PNG");
jop1 = new JOptionPane();
jop3 = new JOptionPane();

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 insat";
stmt.executeUpdate(sql);
System.out.println("Database created successfully...");
sql = "CREATE TABLE insat.etudiant (" +
"cin VARCHAR(8) PRIMARY KEY," +
"numIns VARCHAR(7)," +
"nom VARCHAR(20)," +
"prenom VARCHAR(20)) ";
stmt.executeUpdate(sql);
sql = "CREATE TABLE insat.matiere (" +
"nom_mat VARCHAR(20)," +
"cin VARCHAR(8) REFERENCES etu," +
"ds DECIMAL(5.2)," +
"tp DECIMAL(5.2)," +
"exam DECIMAL(5.2)," +
"CONSTRAINT pk PRIMARY KEY(nom_mat, cin));";
stmt.executeUpdate(sql);
jop1.showMessageDialog(null, "Base de Donnees cree avec succes!", "Information", JOptionPane.INFORMATION_MESSAGE, img);
}catch(SQLException se){
//Handle errors for JDBC
jop3.showMessageDialog(null, "Erreur lors de la creation de la base de donnees : "+se.getMessage(), "Erreur", JOptionPane.ERROR_MESSAGE, img2);
se.printStackTrace();
}catch(Exception e){
//Handle errors for Class.forName
jop3.showMessageDialog(null, "Erreur lors de la creation de la base de donnees : "+e.getMessage(), "Erreur", JOptionPane.ERROR_MESSAGE, img2);
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!");
}
}