Ejemplo JDBC

pom.xml

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
  <modelVersion>4.0.0</modelVersion>

  <groupId>utn.dds.persistencia</groupId>
  <artifactId>que-me-pongo</artifactId>
  <version>1.0-SNAPSHOT</version>
  <packaging>jar</packaging>

  <name>Que Me Pongo</name>

  <properties>
    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
  </properties>

  <dependencies>

    <!-- drivers jdbc -->
    <!-- postgre -->
    <dependency>
        <groupId>org.postgresql</groupId>
        <artifactId>postgresql</artifactId>
        <version>42.2.23</version>
    </dependency>


    <!-- hsqldb -->
    <dependency>
      <groupId>org.hsqldb</groupId>
      <artifactId>hsqldb</artifactId>
      <version>2.4.0</version>
      <scope>test</scope>
    </dependency>

    <!-- dependency test -->

    <dependency>
      <groupId>junit</groupId>
      <artifactId>junit</artifactId>
      <version>4.11</version>
      <scope>test</scope>
    </dependency>

  </dependencies>
  <build>
    <plugins>
        <plugin>
          <groupId>org.apache.maven.plugins</groupId>
          <artifactId>maven-compiler-plugin</artifactId>
          <version>2.3.2</version>
          <configuration>
            <source>1.8</source>
            <target>1.8</target>
          </configuration>
        </plugin>
        <plugin>
          <groupId>com.github.johnpoth</groupId>
          <artifactId>jshell-maven-plugin</artifactId>
          <version>1.3</version>
      </plugin>
    </plugins>
  </build>
</project>

queries.sql

-- ddl ---> create table, create view, ....

create table materiales (
	codigo bigint primary key,
	nombre varchar(255) not null,
	marca varchar(255),
	precio int
)


create table prendas (
	id_prenda bigint primary key,
	nombre character varying(255) not null,
	color character varying(255),
	cod_material bigint references materiales(codigo)
)


--dml  ---> insert -  update - delete - select 


insert into materiales (codigo, nombre, marca, precio) values (3, 'lana', 'ovejita', 150);
insert into materiales (codigo, nombre, marca, precio) values (4, 'cuero', 'vaca feliz', 190);
insert into materiales (codigo, nombre, marca, precio) values (5, 'algodon', 'superhuavechito', 100);


insert into prendas (id_prenda, nombre, color, cod_material) values (4, 'sueter', 'verde', 3)


update materiales set precio = 120 where nombre = 'algodon'


select nombre, precio from materiales where precio > 100


select codigo from materiales where nombre = 'algodon'


select * from prendas where cod_material in (select codigo from materiales where nombre = 'algodon')


select p.nombre as prenda, m.nombre as material, m.precio from prendas p, materiales m where p.cod_material = m.codigo and m.nombre = 'algodon'

script.java

import java.sql.*

Connection connection = DriverManager.getConnection("jdbc:postgresql://localhost/que_me_pongo_2_development", "que_me_pongo_2", "que_me_pongo_2"

PreparedStatement statement = connection.prepareStatement("select * from prendas")

ResultSet result = statement.executeQuery()

result.next()

result.getString("descripcion")

result.close()

statement.close()