I'am working on this source code :
public class AuthentificationClient extends javax.swing.JFrame {
connexion maconn;
Statement stmt1;
public AuthentificationClient() {
initComponents();
}
private void numcompteActionPerformed(java.awt.event.ActionEvent evt) {
// TODO add your handling code here:
}
private void jButton1ActionPerformed(java.awt.event.ActionEvent evt) {
Bienvenue ret = new Bienvenue () ;
ret.setVisible(true);
this.dispose();
}
private void jButton2ActionPerformed(java.awt.event.ActionEvent evt) {
String requete ="Select * from Compte where numcompte='"+numcompte.getText()+"' and codec = '"+Arrays.toString(code.getPassword())+"'";
try {
Statement stmt1 = maconn.Obtenirconnexion().createStatement();
ResultSet rs= stmt1.executeQuery(requete);
} catch (SQLException ex) {
Logger.getLogger(AuthentificationPharmacien.class.getName()).log(Level.SEVERE, null, ex);
}
OpClient oc = new OpClient () ;
oc.setVisible(true);
this.dispose();
}
/* Create and display the form */
java.awt.EventQueue.invokeLater(new Runnable() {
public void run() {
new AuthentificationClient().setVisible(true);
}
});
}
There is no error but when I execute, it doesn't work correctly! This is the error message that I receive :
The variable maconn is never assigned, at least in the code you have provided, so you may be calling a method on a null object.
Use PreparedStatement instead of Statement to avoid SQL Injection attack as well to simplify your code e.g. you won't need to enclose string literals within ' ' when you use PreparedStatement.
Perform null check on an object (e.g. maconn) before accessing any member (method/variable) using it.
Do it as follows:
String requete ="Select * from Compte where numcompte = ? and codec = ?";
PreparedStatement pstmt;
ResultSet rs;
try {
if(maconn!=null && maconn.Obtenirconnexion()!=null) {
pstmt = maconn.Obtenirconnexion().prepareStatement(requete);
pstmt.setString(1, numcompte.getText());
pstmt.setString(2, Arrays.toString(code.getPassword()));
rs = pstmt.executeQuery(requete);
//...
}
}
Related
I am trying to output the first column (nameID) of my table (StudentInfo) in my database. But the statement.executeQuery is not working and ResultSet.next() is false.
Java NetBeans program
Calls sqlite database
Uses "jdbc:sqlite:ProjectWeekDB.sqlite" as url
private static Connection connection = null;
private static PreparedStatement stmt = null;
private static Statement statement = null;
private static ResultSet results = null;
public static void createNewDatabase() {
String sqlData = "SELECT * FROM StudentInfo";
String url;
try {
connection = DriverManager.getConnection(url);
if (connection != null) {
statement = connection.createStatement();
stmt = connection.prepareStatement(sqlData);
statement.executeUpdate(sqlData);
results = statement.executeQuery(sqlData);
while (results.next()) {
print(results.getInt("nameID"));
}
stmt.close();
results.close();
}
} catch (SQLException e) {
print(e.getMessage());
}
}
public static void main(String[] args) {
createNewDatabase();
}
It just prints out BUILD successful without actually displaying the first column in the database.
I am designing a simple database application that features 2 jComboBoxes in the GUI. The first jComboBox is populated with the results of an SQL query. I would like the second jComboBox to populate with the results of a second query that incorporates the user selected value in the first box, but I can't quite get it to work.
I have created 2 classes, one that draws the GUI and contains the main method, and a second class that queries my Oracle database.
My GUI class:
public class TestUI extends javax.swing.JFrame {
// Create new form TestUI
public TestUI() {
initComponents();
}
#SuppressWarnings("unchecked")
private void initComponents() {
jPanel1 = new javax.swing.JPanel();
jComboBox1 = new javax.swing.JComboBox<>();
jTextField1 = new javax.swing.JTextField();
jComboBox2 = new javax.swing.JComboBox<>();
jButton1 = new javax.swing.JButton();
jButton2 = new javax.swing.JButton();
setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);
// Combo box 1 population
jComboBox1.removeAllItems();
createConnection c1 = new createConnection();
c1.getEmployee().forEach((employee) -> {
jComboBox1.addItem(employee);
});
jComboBox1.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
jComboBox1ActionPerformed(evt);
}
});
// ComboBox 2 population
jComboBox2.removeAllItems();
}
private void jComboBox1ActionPerformed(java.awt.event.ActionEvent evt) {
// TODO add handling code here:
}
public static void main(String args[]) {
DRAW GUI
}
}
And my database class:
import java.util.List;
import java.util.ArrayList;
import java.sql.*;
public class createConnection {
String empName;
public Connection createConnection() {
try {
Class.forName(driver);
java.sql.Connection conn = DriverManager.getConnection(DB_URL, DB_username, DB_password);
return conn;
} catch (ClassNotFoundException | SQLException e) {
return null;
}
}
// ComboBox 1
public List<String> getEmployee() {
List<String> list = new ArrayList();
Connection conn = createConnection();
try {
Statement stmt = conn.createStatement();
String query = "SELECT * FROM hr.employees ORDER BY last_name";
ResultSet results = stmt.executeQuery(query);
while (results.next()) {
list.add(results.getString("last_name"));
}
} catch (Exception e) {
System.out.println("Exception = " + e);
}
return list;
}
// Combo Box 2
public List<String> getEmpLocation() {
List<String> list = new ArrayList();
Connection conn = createConnection();
try {
Statement stmt = conn.createStatement();
String query = "SELECT country_id FROM hr.location WHERE hr.location.emp_name = " + empName;
ResultSet results = stmt.executeQuery(query);
while (results.next()) {
list.add(results.getString("last_name"));
}
} catch (Exception e) {
System.out.println("Exception = " + e);
}
return list;
}
}
I have left out irrelevant code like db connection variables and GUI coordinates etc.
I am wondering how to properly get the getEmpLocation() method in the database class to populate the 2nd ComboBox. This will involve adding code to both classes and passing the variable value but I can't figure it out! Any help would be greatly appreciated here.
I'm assuming that you'd like select a value from your first JComboBox then click on a button to process your selected data and load new data to your second JComboBox.
In this case you need an ActionListener to your JButton instead of your JComboBox:
jButton1.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
selectedName = (String) jComboBox1.getSelectedItem();
}
});
You also need to store your selected value in a variable. The getSelectedItem() method returns an Object so it needs to be cast to a String in your case.
Since we added an ActionListener to a button you dont need this one:
jComboBox1.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
jComboBox1ActionPerformed(evt);
}
});
In your createConnection class (by naming convention class names should start with a capital letter):
If you are not using try-with-resources statement you should close your connections after the catch block.
} finally {
if (conn != null) {
try {
conn.close();
} catch (SQLException ex) {
ex.printStackTrace();
}
}
}
You need to pass your selectedName variable to getEmpLocation() method:
public List<String> getEmpLocation(String name) {
You should use a PreparedStatement instead of Statement:
String query = "SELECT first_name FROM employees WHERE last_name = ?";
PreparedStatement ps = conn.prepareStatement(query);
ps.setString(1, name);
ResultSet results = ps.executeQuery();
To be honest I don't know what you'd like to achieve with your select queries. First, this select query won't work. Table name is LOCATIONS instead of location, and it doesnt have a column called emp_name.
"SELECT country_id FROM hr.location WHERE hr.location.emp_name = ?"
If you'd like to get locations you should use a query like this:
"SELECT dep.department_name, loc.city, cou.country_name
FROM employees emp, departments dep, locations loc, countries cou
WHERE emp.last_name = ?
AND emp.department_id = dep.department_id
AND dep.location_id = loc.location_id
AND loc.country_id = cou.country_id"
You can choose which location you'd like to use department, city or country name. But my main problem is that if you select last names first and put them in a JComboBox it is most likely you will get only one row of data, so there is no point in using the second JComboBox. Let's approach this problem from the other side. What if you select location first and then select your employee. That could solve this issue.
Quick Example:
You select all first names from database, then you can select proper last name.
Selecting all first name from database:
public List<String> getEmpFirstName() {
List<String> list = new ArrayList();
Connection conn = createConnection();
try {
Statement stmt = conn.createStatement();
String query = "SELECT DISTINCT first_name "
+ "FROM hr.employees "
+ "ORDER BY first_name";
ResultSet results = stmt.executeQuery(query);
while (results.next()) {
list.add(results.getString("first_name"));
}
} catch (Exception e) {
System.out.println("Exception = " + e);
} finally {
if (conn != null) {
try {
conn.close();
} catch (SQLException ex) {
ex.printStackTrace();
}
}
}
return list;
}
Selecting last name(s) based on first name using PreparedStatement:
public List<String> getEmpLastName(String name) {
List<String> list = new ArrayList();
Connection conn = createConnection();
try {
String query = "SELECT last_name "
+ "FROM employees "
+ "WHERE first_name = ?";
PreparedStatement ps = conn.prepareStatement(query);
ps.setString(1, name);
ResultSet results = ps.executeQuery();
while (results.next()) {
list.add(results.getString("last_name"));
}
} catch (Exception e) {
System.out.println("Exception = " + e);
} finally {
if (conn != null) {
try {
conn.close();
} catch (SQLException ex) {
ex.printStackTrace();
}
}
}
return list;
}
Update your ActionListener:
jButton1.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
// Store selected value
selectedName = (String) jComboBox1.getSelectedItem();
// Create Connection and pass selected value to getEmpLastName
createConnection c1 = new createConnection();
names = c1.getEmpLastName(selectedName);
// Clear your second comboBox and fill with data
jComboBox2.removeAllItems();
for (String lastName : names) {
jComboBox2.addItem(lastName);
}
}
});
Try to select common names like Alexander, David, James, John, Julia and so on.
I am having problems inserting data into a postgres table created using java. The created table part of the code works fine, its only when I am inserting values into the table that nothing happens. The code I am using to populate the table tt is:
private void jButton1ActionPerformed(java.awt.event.ActionEvent evt) {
String txt1 = jTextField1.getText();
int number = Integer.parseInt(txt1);
String name= jTextField2.getText();
String txt3 = jTextField3.getText();
int mean = Integer.parseInt(txt3);
Connection c = null;
Statement stmt = null;
try {
Class.forName("org.postgresql.Driver");
c = DriverManager.getConnection("jdbc:postgresql://localhost:5432/tst", "postgres", "21262050");
c.setAutoCommit(false);
System.out.println("Opened database successfully");
String sql = "INSERT INTO tt(noun, max, nbr) VALUES(?, ?, ?)";
PreparedStatement pst = c.prepareStatement(sql);
pst.setString(1, name);
pst.setInt(2,mean );
pst.setInt(3, number);
pst.executeUpdate();
} catch (SQLException ex) {
Logger.getLogger(insrt.class.getName()).log(Level.SEVERE, null, ex);
}
catch(Exception e){
e.printStackTrace();
}
}
public static void main(String args[]) {
java.awt.EventQueue.invokeLater(new Runnable() {
public void run() {
new insrt().setVisible(true);
}
});
}
You're establishing autocommit to false.
After the auto-commit mode is disabled, no SQL statements are
committed until you call the method commit explicitly.
https://docs.oracle.com/javase/tutorial/jdbc/basics/transactions.html#disable_auto_commit
Try executing c.commit() after pst.executeUpdate();
What is the problem in this code? where it is update the all column values with the same last one .
public class dbconnection {
java.sql.Connection con;
java.sql.Statement st;
ResultSet rs;
public EncBean getConnection()throws SQLException{
EncBean encBean1 = new EncBean();
String v_url= "jdbc:oracle:thin:#192.168.2.138:1522:orcl2";
String v_username= "scott";
String v_password = "tiger";
try
{
DriverManager.registerDriver(new oracle.jdbc.OracleDriver());
con = DriverManager.getConnection(v_url,v_username,v_password);
System.out.println ("Connection to Oracle database was Established");
}
catch ( SQLException e)
{
e.printStackTrace();
}
return encBean1;
}
public EncBean selectRows()
{
EncBean encBean2 = new EncBean();
try
{
String SQLselect="select JOB_NAME from job";
st=con.createStatement();
rs=st.executeQuery(SQLselect);
while (rs.next()) {
encBean2.setName(rs.getString("JOB_NAME"));
}
}
catch ( Exception ex )
{
ex.printStackTrace();
}
return encBean2;
}
public void updateRows(String updatedname){
try
{
Statement stmt = con.createStatement(ResultSet.TYPE_FORWARD_ONLY,ResultSet.CONCUR_UPDATABLE);
ResultSet srs = stmt.executeQuery("select job_name from job " );
while (srs.next()) {
srs.updateString("job_name", updatedname);
srs.updateRow();
con.commit();}
System.out.println("An existing user was updated successfully!");}
catch(SQLException err){
System.out.println(err.getMessage());
}}}
This is the main
public class mainenc {
public static void main(String[] args) throws Exception{
dbconnection dbcon = new dbconnection();
EncBean encbeancon= dbcon.getConnection();
EncBean encBean5 = dbcon.selectRows();
enc concatinputs = new enc();
EncBean encBeanconcat = concatinputs.funconcat(encBean5.getName());
EncBean encBean4 = concatinputs.inputencryption(encBeanconcat.getConcatenatedData());
String vReserverbin= encBean4.getReversedBinary();
String ascistring= concatinputs.convertBinaryStringToString(vReserverbin);
dbcon.updateRows(ascistring);
}}
What is the problem in this code? where it is update the all column values with the same last one .
After updated method you should write list method again.
Try to take this example:
UPDATE tableB
SET tableB.value , tableA.value, tableB.value)
WHERE tableA.name = 'Joe'
It is kind of obvious: dbcon.updateRows(...) calls for the update method and that method does the job.
But as Erhan said, you don't get to see the result because you don't actually make use of updated records, e.g. show them etc. At least, you can check it out at the DB level if op is completed.
But I really disliked your comment:
plz can you do it for me?
You should do your own task and ask help when you need a hand. But never expect someone else to do your job mate.
I confused with this if-else because I'm new in Java & MySQL and I tried to make it by myself.
public Menu() {
initComponents();
try {
Class.forName("com.mysql.jdbc.Driver");
con = DriverManager.getConnection("jdbc:mysql://localhost:3306/restaurant", "root", "");
System.out.println("ODBC Connection Successful");
showCategory();
} catch (ClassNotFoundException | SQLException e) {
System.out.println("ODBC Connection Failed" + e);
}
}
if - else
private void showCategory() {
try {
Statement stmt;
stmt = con.createStatement();
if (rbMFood.isSelected()) {
ResultSet rs = stmt.executeQuery("SELECT * FROM menu_cat WHERE type_id = 'TY02'");
while (rs.next()) {
cmbMCat.addItem(rs.getString("menu_cat"));
}
} else {
ResultSet rs = stmt.executeQuery("SELECT * FROM menu_cat WHERE type_id = 'TY01'");
while (rs.next()) {
cmbMCat.addItem(rs.getString("menu_cat"));
}
}
} catch (Exception e) {
}
}
Radio Button
private void rbMFoodActionPerformed(java.awt.event.ActionEvent evt) {
// TODO add your handling code here:
type = "Food";
}
private void rbMDrinkActionPerformed(java.awt.event.ActionEvent evt) {
// TODO add your handling code here:
type = "Drink";
}
And I declare the function in the end of the program
private String type;
When I click drink / food, the category still drink's category.
The database
Any help would be greatly appreciated!
You are using rs.getString("menu_cat") But the format is rs.getString(<Column Name>) But you are using rs.getString(<Table Name>) As "menu_cat" is name of the table and not the name of the column.
AFTER POSTING CONSTRUCTOR
What I see from the code you have posted, is that You have called showCategory() in the constructor. This method is responsible for populating the JComboBox cmbMCat. Now the cmbMCat is being populated when you are creating the new Menu. After that the items list of the cmbMCat does not change.
So, What I suggest is that you call the showCategory() from the rbMFoodActionPerformed and rbMDrinkActionPerformed methods. I hope this will solve your problem.
Also add cmbMCat.removeAllItems() before Statement stmt; to remove all the items that are there in the cmbMCat and reset it with a fresh list of items.
After comment regarding the if-else
Change the showCatagory() as below:
private void showCategory() {
cmbMCat.removeAllItems();
try {
PreparedStatement stmt; //Used Prepared statement
String sql = "SELECT * FROM menu_cat WHERE type_id = ?";
stmt = con.prepareStatement(sql);
if (type.equals("Drink")) {
stmt.setString("TY01");
} else {
stmt.setString("TY02");
}
ResultSet rs = stmt.executeQuery();
while (rs.next()) {
cmbMCat.addItem(rs.getString("menu_cat"));
}
}
} catch (Exception e) {
}
}
Also note that you eventListener code should be:
private void rbMFoodActionPerformed(java.awt.event.ActionEvent evt){
type = "Food";
showCategory();
}
private void rbMDrinkActionPerformed(java.awt.event.ActionEvent evt){
type = "Drink";
showCategory();
}