emrodriguez

public class Conexion {
  private static Conexion instancia;
  
  private Conexion() {}
  
  public static Conexion getInstancia() {
    if(instancia == null) {
      instancia = new Conexcion();
    } 
    return instancia;

emrodriguez

public class ConexcionFabrica {
  
  public IConexion getConexion(String motor) {
    switch(motor) {
      case "MYSQL": return new ConexionMySQL();
      case "Oracle": return new ConexionOracle();
      default: return null;
    }
  }

emrodriguez

ALTER TABLE TABLE_NAME
	ADD NEW_COLUMN INTEGER REFERENCES TABLE_REFERENCE(ID_PRIMARY_KEY);