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- retrieving values from database in java
- import java.sql.*;
- public class GuestsInfo
- {
- private String firstName, lastName;
- private int age;
- private Connection con;
- private PreparedStatement statement;
- public GuestsInfo()
- {
- try {
- Class.forName("com.mysql.jdbc.Driver");
- con = DriverManager.getConnection(
- "jdbc:mysql://localhost:3306/3moronsdb","root","");
- } catch (Exception e) {
- e.printStackTrace();
- }
- }
- public GuestsInfo(String firstName, String lastName, int age)
- {
- this();
- try
- {
- statement = con.prepareStatement("Insert into guest(firstName,lastName,age)values(?,?,?)");
- statement.setString(1, firstName);
- statement.setString(2, lastName);
- statement.setInt(3, age);
- statement.executeUpdate();
- con.close();
- }
- catch(Exception e)
- {
- e.printStackTrace();
- return;
- }
- }
- public void setFirstName(String firstName)
- {
- try{
- statement= con.prepareStatement("SELECT * FROM guest WHERE firstName = ?");
- statement.setString(1, firstName);
- ResultSet rs = statement.executeQuery();
- while(rs.next()){
- firstName = rs.getString(1);
- }
- }catch(Exception e){
- System.out.print(e);
- }
- }
- public String getFirstName(){
- return firstName;
- }
- public void setLastName(String lastName)
- {
- try{
- statement= con.prepareStatement("SELECT * FROM guest WHERE lastName = ?");
- statement.setString(2, lastName);
- ResultSet rs = statement.executeQuery();
- while(rs.next()){
- lastName = rs.getString(2);
- }
- }catch(Exception e){
- System.out.print(e);
- }
- }
- public String getLastName(){
- return lastName;
- }
- public void setAge(int age){
- try{
- statement = con.prepareStatement("SELECT * FROM guest WHERE age=?");
- statement.setInt(3, age);
- ResultSet rs = statement.executeQuery();
- while(rs.next()){
- age = rs.getInt(3);
- }
- }catch(Exception e){
- System.out.print(e);
- }
- }
- public int getAge(){
- return age;
- }
- public class TestMain {
- public static void main(String [] args){
- GuestsInfo gi = new GuestsInfo();
- gi.setFirstName("Ericka");
- System.out.println(gi.getFirstName());
- }
- }
- public void setFirstName(String firstName)
- {
- try{
- // Here you create a READing statement.
- statement= con.prepareStatement("SELECT * FROM guest WHERE firstName = ?");
- statement.setString(1, firstName);
- ResultSet rs = statement.executeQuery();
- while(rs.next()){
- // Here you set the >>method param<< to a non-existing String
- firstName = rs.getString(1);
- }
- }catch(Exception e){
- System.out.print(e);
- }
- }
- // After the method is done you have done nothing because you didn't even set your class member variable "firstName", which you would have set using "this.firstName".
- GuestsInfo gi = new GuestsInfo("Ericka", "Something", 30);
- GuestsInfo gi = new GuestsInfo();
- GuestsInfo gi = new GuestsInfo("Ericka", "lastName", 23);
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