Update database-integration.md

Syncing with the English version of the document, in regards to integration with PostgreSQL.

es/guide/database-integration.md

@@ -226,12 +226,12 @@ apoc.query('match (n) return n').exec().then(
 
 ## PostgreSQL
 
-**Módulo**: [pg](https://github.com/brianc/node-postgres)
+**Módulo**: [pg-promise](https://github.com/vitaly-t/pg-promise)
 **Instalación**
 
 <pre>
 <code class="language-sh" translate="no">
-$ npm install pg
+$ npm install pg-promise
 </code>
 </pre>
 
@@ -239,23 +239,16 @@ $ npm install pg
 
 <pre>
 <code class="language-javascript" translate="no">
-var pg = require('pg');
-var conString = "postgres://username:password@localhost/database";
+var pgp = require("pg-promise")(/*options*/);
+var db = pgp("postgres://username:password@host:port/database");
 
-pg.connect(conString, function(err, client, done) {
-
-  if (err) {
-    return console.error('error fetching client from pool', err);
-  }
-  client.query('SELECT $1::int AS number', ['1'], function(err, result) {
-    done();
-    if (err) {
-      return console.error('error running query', err);
-    }
-    console.log(result.rows[0].number);
-  });
-
-});
+db.one("SELECT $1 AS value", 123)
+    .then(function (data) {
+        console.log("DATA:", data.value);
+    })
+    .catch(function (error) {
+        console.log("ERROR:", error);
+    });
 </code>
 </pre>