DB_EnterpriseH2

Overview

The DB_EnterpriseH2 class is a complete enterprise database management system using H2 Database Engine. It provides the same functionality as DB_EnterpriseHSQLDB but optimized for H2, including automatic database file cleanup and file-based storage.

Class Information

Class

public class

DB_EnterpriseH2JDBC Driver: org.h2.Driver

Database Constants

URL

String

H2 database connection URL with auto-server mode and persistent connection

private static final String URL = "jdbc:h2:file:./db_empresa_h2;AUTO_SERVER=TRUE;DB_CLOSE_DELAY=-1";

AUTO_SERVER

boolean

default:"TRUE"

Enables multiple concurrent connections to the same database

DB_CLOSE_DELAY

int

default:"-1"

Keeps database open until JVM shutdown (-1 = never auto-close)

USER

String

default:"SA"

Database username constant

private static final String USER = "SA";

PASSWORD

String

default:""

Database password (empty by default)

private static final String PASSWORD = "";

Main Method

Signature

public static void main(String[] args)

Workflow

Class.forName("org.h2.Driver");

Core Methods

eliminarArchivosBD()

private static void eliminarArchivosBD()

Purpose

Deletes existing H2 database files before creating a fresh database

Files Removed

db_empresa_h2.mv.db - Main database file
db_empresa_h2.trace.db - Trace/log file

Implementation

File dbFile1 = new File("db_empresa_h2.mv.db");
File dbFile2 = new File("db_empresa_h2.trace.db");

if (dbFile1.exists()) {
    if (dbFile1.delete()) {
        System.out.println("Archivo de BD anterior eliminado: " + dbFile1.getName());
    } else {
        System.out.println("No se pudo eliminar el archivo: " + dbFile1.getName());
    }
}

if (dbFile2.exists()) {
    if (dbFile2.delete()) {
        System.out.println("Archivo de trazas eliminado: " + dbFile2.getName());
    }
}

inicializarBaseDatos()

private static void inicializarBaseDatos()

Purpose

Checks if tables exist and creates the complete schema if needed

Implementation

DatabaseMetaData meta = conn.getMetaData();
ResultSet tables = meta.getTables(null, null, "T_EMPLEADOS", null);

if (!tables.next()) {
    crearEsquemaCompleto(conn);
    System.out.println("Creando base de datos H2...");
} else {
    System.out.println("Base de datos H2 ya existe.");
}

crearEsquemaCompleto()

private static void crearEsquemaCompleto(Connection conn) throws SQLException

conn

Connection

required

Active H2 database connection

Tables Created

t_centros - Work centers/locations
t_departamentos - Departments with foreign key to centers
t_empleados - Employees with foreign key to departments

Schema Structure

CREATE TABLE t_centros (
    codigo_centro INTEGER PRIMARY KEY,
    nombre_centro VARCHAR(21) NOT NULL,
    ubicacion VARCHAR(50) NOT NULL
)

menuPrincipal()

private static void menuPrincipal()

Ver empleados
Agregar empleado
Buscar empleados
Ver departamentos
Eliminar empleado
Información completa con JOINs
Salir

CRUD Operations

verEmpleados()

private static void verEmpleados()

SQL Query

String sql = "SELECT e.*, d.nombre_departamento FROM t_empleados e " +
            "JOIN t_departamentos d ON e.codigo_departamento = d.codigo_departamento";

Displays employee information with department names using JOIN

agregarEmpleado()

private static void agregarEmpleado()

User Input

Interactive

Código (Employee ID)
Departamento (Department ID)
Nombre (Employee Name)
Salario (Base Salary)
Fecha ingreso (Hire Date in YYYY-MM-DD format)

Parameterized Insert

String sql = "INSERT INTO t_empleados (codigo_empleado, codigo_departamento, " +
            "extension_telefonica_empleado, fecha_nacimiento_empleado, " +
            "fecha_ingreso_empleado, salario_base_empleado, comision_empleado, " +
            "numero_hijos_empleado, nombre_empleado) VALUES (?, ?, 100, '1990-01-01', ?, ?, 0, 0, ?)";

pstmt.setInt(1, codigo);        // Employee code
pstmt.setInt(2, depto);         // Department code
pstmt.setString(3, fecha);      // Hire date
pstmt.setDouble(4, salario);    // Salary
pstmt.setString(5, nombre);     // Name
pstmt.executeUpdate();

buscarEmpleados()

private static void buscarEmpleados()

nombre

String

Partial name for LIKE search

Search Implementation

String sql = "SELECT * FROM t_empleados WHERE nombre_empleado LIKE ?";
pstmt.setString(1, "%" + nombre + "%");
ResultSet rs = pstmt.executeQuery();

verDepartamentos()

private static void verDepartamentos()

Output

Lists all departments with ID, name, and budget information

Query

String sql = "SELECT * FROM t_departamentos";

eliminarEmpleado()

private static void eliminarEmpleado()

codigo

int

required

Employee code to delete from the database

Delete Implementation

String sql = "DELETE FROM t_empleados WHERE codigo_empleado = ?";
ps.setInt(1, codigo);
int filasAfectadas = ps.executeUpdate();

if (filasAfectadas > 0) {
    System.out.println("Empleado eliminado correctamente");
} else {
    System.out.println("No se encontró el empleado con ese código");
}

informacionCompletaJoins()

private static void informacionCompletaJoins()

Purpose

Displays comprehensive employee information by joining three tables

Triple JOIN Query

String sql = "SELECT " +
            "e.codigo_empleado, " +
            "e.nombre_empleado, " +
            "e.salario_base_empleado, " +
            "e.fecha_ingreso_empleado, " +
            "d.nombre_departamento, " +
            "d.presupuesto_departamento, " +
            "c.nombre_centro, " +
            "c.ubicacion " +
            "FROM t_empleados e " +
            "JOIN t_departamentos d ON e.codigo_departamento = d.codigo_departamento " +
            "JOIN t_centros c ON d.codigo_centro = c.codigo_centro " +
            "ORDER BY e.codigo_empleado";

Joins

Employee → Department (via codigo_departamento)
Department → Center (via codigo_centro)

Sample Data

The database is populated with initial data during creation:

Centers (t_centros)

INSERT INTO t_centros VALUES (10, 'SEDE CENTRAL', 'C/ ALCALA, 820, MADRID');
INSERT INTO t_centros VALUES (20, 'RELACION CON CLIENTES', 'C/ ATOCHA, 405, MADRID');

Departments (t_departamentos)

Eight departments including:

100: DIRECCION GENERAL (Budget: 120,000)
110: DIRECCION COMERCIAL (Budget: 15,000)
111: SECTOR INDUSTRIAL (Budget: 11,000)
112: SECTOR SERVICIOS (Budget: 9,000)
120: ORGANIZACION (Budget: 3,000)
121: PERSONAL (Budget: 2,000)
122: PROCESO DE DATOS (Budget: 6,000)
130: FINANZAS (Budget: 2,000)

Employees (t_empleados)

Six employees with complete information:

110: PONS, CESAR (Salary: 3,100, Dept: 121 PERSONAL)
120: LASA, MARIO (Salary: 3,500, Dept: 112 SECTOR SERVICIOS)
130: TEROL, LUCIANO (Salary: 2,900, Dept: 112 SECTOR SERVICIOS)
150: PEREZ, JULIO (Salary: 4,400, Dept: 121 PERSONAL)
160: AGUIRRE, AUREO (Salary: 3,100, Dept: 111 SECTOR INDUSTRIAL)
180: PEREZ, MARCOS (Salary: 4,800, Dept: 110 DIRECCION COMERCIAL)

H2-Specific Features

File Storage

File

Database stored in db_empresa_h2.mv.db file

AUTO_SERVER

boolean

default:"TRUE"

Allows multiple JVMs to connect to the same database file simultaneously

DB_CLOSE_DELAY

int

default:"-1"

Prevents automatic database closure when last connection closes

Error Handling

catch (SQLException e) {
    System.out.println("Error: " + e.getMessage());
}

Differences from HSQLDB Version

Feature	DB_EnterpriseH2	DB_EnterpriseHSQLDB
Driver	org.h2.Driver	org.hsqldb.jdbc.JDBCDriver
URL Format	jdbc:h2:file	jdbc:hsqldb:file
Auto Server	AUTO_SERVER=TRUE	N/A
File Cleanup	eliminarArchivosBD()	No cleanup
Config File	Hardcoded URL	config.ini
Table Check	T_EMPLEADOS	T_CENTROS

DB_Enterprise - Basic configuration manager
DB_EnterpriseHSQLDB - HSQLDB implementation

Getting Started

Core Components

Database Operations

Examples

API Reference

Overview

Class Information

Database Constants

Main Method

Signature

Workflow

Core Methods

eliminarArchivosBD()

inicializarBaseDatos()

crearEsquemaCompleto()

menuPrincipal()

CRUD Operations

verEmpleados()

agregarEmpleado()

buscarEmpleados()

verDepartamentos()

eliminarEmpleado()

informacionCompletaJoins()

Sample Data

H2-Specific Features

Error Handling

Differences from HSQLDB Version

Build docs developers (and LLMs) love

Getting Started

Core Components

Database Operations

Examples

API Reference

​Overview

​Class Information

​Database Constants

​Main Method

​Signature

​Workflow

​Core Methods

​eliminarArchivosBD()

​inicializarBaseDatos()

​crearEsquemaCompleto()

​menuPrincipal()

​CRUD Operations

​verEmpleados()

​agregarEmpleado()

​buscarEmpleados()

​verDepartamentos()

​eliminarEmpleado()

​informacionCompletaJoins()

​Sample Data

​H2-Specific Features

​Error Handling

​Differences from HSQLDB Version

​Related Classes

Build docs developers (and LLMs) love

Overview

Class Information

Database Constants

Main Method

Signature

Workflow

Core Methods

eliminarArchivosBD()

inicializarBaseDatos()

crearEsquemaCompleto()

menuPrincipal()

CRUD Operations

verEmpleados()

agregarEmpleado()

buscarEmpleados()

verDepartamentos()

eliminarEmpleado()

informacionCompletaJoins()

Sample Data

H2-Specific Features

Error Handling

Differences from HSQLDB Version

Related Classes