diff --git a/src/Libs/ModelMySQL.php b/src/Libs/ModelMySQL.php
index 512b1d5..cd6b39c 100644
--- a/src/Libs/ModelMySQL.php
+++ b/src/Libs/ModelMySQL.php
@@ -43,10 +43,10 @@ class ModelMySQL {
   * @return mysqli
   */
   private static function db(){
-    if (is_null(self::$db))
-      self::$db = Database::getConnection();
+    if (is_null(static::$db))
+      static::$db = Database::getConnection();
 
-    return self::$db;
+    return static::$db;
   }
   
   /*
@@ -62,7 +62,7 @@ class ModelMySQL {
   *   Contiene el resultado de la llamada SQL.
   */
   private static function query($query){
-    $db = self::db();
+    $db = static::db();
     
     $result = $db->query($query);
     if ($db->errno){
@@ -82,7 +82,7 @@ class ModelMySQL {
   * Reinicia la configuración de la sentencia SQL.
   */
   private static function resetQuery(){
-    self::$querySelect = [
+    static::$querySelect = [
                     'select' => '*',
                     'where' => '',
                     'leftJoin' => '',
@@ -96,44 +96,44 @@ class ModelMySQL {
   }
   
   /*
-  * Construye la sentencia SQL a partir self::$querySelect y una vez
+  * Construye la sentencia SQL a partir static::$querySelect y una vez
   * construída, llama a resetQuery.
   *
   * @return string
   *   Contiene la sentencia SQL.
   */
   private static function buildQuery(){
-    $sql = 'SELECT '.self::$querySelect['select'].' FROM '.self::table();
+    $sql = 'SELECT '.static::$querySelect['select'].' FROM '.static::table();
     
-    if (self::$querySelect['leftJoin'] != ''){
-      $sql .= ' LEFT JOIN ' . self::$querySelect['leftJoin'];
-      $sql .= ' ON '. self::$querySelect['on'];
-    } elseif(self::$querySelect['rightJoin'] != ''){
-      $sql .= ' RIGHT JOIN ' . self::$querySelect['leftJoin'];
-      $sql .= ' ON '. self::$querySelect['on'];
+    if (static::$querySelect['leftJoin'] != ''){
+      $sql .= ' LEFT JOIN ' . static::$querySelect['leftJoin'];
+      $sql .= ' ON '. static::$querySelect['on'];
+    } elseif(static::$querySelect['rightJoin'] != ''){
+      $sql .= ' RIGHT JOIN ' . static::$querySelect['leftJoin'];
+      $sql .= ' ON '. static::$querySelect['on'];
     }
     
-    if (self::$querySelect['where'] != ''){
-      $sql .= ' WHERE '.self::$querySelect['where'];
+    if (static::$querySelect['where'] != ''){
+      $sql .= ' WHERE '.static::$querySelect['where'];
       
-      if (self::$querySelect['AndOr'] != ''){
-        $sql .= self::$querySelect['AndOr'];
+      if (static::$querySelect['AndOr'] != ''){
+        $sql .= static::$querySelect['AndOr'];
       }
     }
     
-    if (self::$querySelect['groupBy'] != ''){
-      $sql .= ' GROUP BY '.self::$querySelect['groupBy'];
+    if (static::$querySelect['groupBy'] != ''){
+      $sql .= ' GROUP BY '.static::$querySelect['groupBy'];
     }
     
-    if (self::$querySelect['orderBy'] != ''){
-      $sql .= ' ORDER BY '.self::$querySelect['orderBy'];
+    if (static::$querySelect['orderBy'] != ''){
+      $sql .= ' ORDER BY '.static::$querySelect['orderBy'];
     }
     
-    if (self::$querySelect['limit'] != ''){
-      $sql .= ' LIMIT '.self::$querySelect['limit'];
+    if (static::$querySelect['limit'] != ''){
+      $sql .= ' LIMIT '.static::$querySelect['limit'];
     }
     
-    self::resetQuery();
+    static::resetQuery();
     
     return $sql;
   }
@@ -186,16 +186,16 @@ class ModelMySQL {
   }
   
   /*
-  * Construye (a partir del nombre de la clase y el sufijo en self::$tableSufix) 
+  * Construye (a partir del nombre de la clase y el sufijo en static::$tableSufix) 
   * y/o develve el nombre de la tabla de la BD en la que se alojará o
   * se aloja el objeto actual.
   * 
   * @return string
   */
   private static function table(){
-    if (isset(self::$table))
-      return self::$table;
-    return self::className().self::$tableSufix;
+    if (isset(static::$table))
+      return static::$table;
+    return static::className().static::$tableSufix;
   }
 
   /*
@@ -205,15 +205,15 @@ class ModelMySQL {
     $atts = $this->getVars();
     
     foreach ($atts as $key => $value){
-      $value = self::db()->real_escape_string($value);
+      $value = static::db()->real_escape_string($value);
       $set[]="$key='$value'";
     }
     
-    $table = self::table();
+    $table = static::table();
     $pk = $this->primaryKey;
     $pkv = $this->$pk;
     $sql = "UPDATE $table SET ".join(', ', $set)." WHERE $pk='$pkv'";
-    self::query($sql);
+    static::query($sql);
   }
   
   /*
@@ -221,7 +221,7 @@ class ModelMySQL {
   * objeto actual.
   */
   private function add(){
-    $db = self::db();
+    $db = static::db();
     $atts = $this->getVars();
     
     foreach ($atts as $key => $value){
@@ -229,9 +229,9 @@ class ModelMySQL {
       $values[] = "'".$db->real_escape_string($value)."'";
     }
     
-    $table = self::table();
+    $table = static::table();
     $sql = "INSERT INTO $table (".join(', ', $into).") VALUES (".join(', ', $values).")";
-    self::query($sql);
+    static::query($sql);
     
     $pk = $this->primaryKey;
     $this->$pk = $db->insert_id;
@@ -256,15 +256,15 @@ class ModelMySQL {
     $atts = $this->getVars();
     
     foreach ($atts as $key => $value){
-      $value = self::db()->real_escape_string($value);
+      $value = static::db()->real_escape_string($value);
       $set[]="$key='$value'";
     }
     
-    $table = self::table();
+    $table = static::table();
     $pk = $this->primaryKey;
     $pkv = $this->$pk;
     $sql = "DELETE FROM $table WHERE $pk='$pkv'";
-    self::query($sql);
+    static::query($sql);
   }
   
   /*
@@ -274,13 +274,13 @@ class ModelMySQL {
   *   Columnas que se selecionarán en la consulta SQL.
   */
   public static function select($columns){
-    $db = self::db();
+    $db = static::db();
     $select = [];
     foreach($columns as $column){
       $select[] = $db->real_escape_string($column);
     }
     
-    self::$querySelect['select'] = join(', ', $select);
+    static::$querySelect['select'] = join(', ', $select);
     
     return new static();
   }
@@ -298,8 +298,8 @@ class ModelMySQL {
   *   El valor el valor a comparar en la columna.
   *
   * Sintaxis posibles: 
-  *  - self::where(columna, operador, valor)
-  *  - self::where(columna, valor)  // Operador por defecto "="
+  *  - static::where(columna, operador, valor)
+  *  - static::where(columna, valor)  // Operador por defecto "="
   */
   public static function where($column, $operator, $value=null){
     if (is_null($value)){
@@ -307,9 +307,9 @@ class ModelMySQL {
       $operator = '=';
     }
     
-    $value = self::db()->real_escape_string($value);
+    $value = static::db()->real_escape_string($value);
     
-    self::$querySelect['where'] = "$column$operator'$value'";
+    static::$querySelect['where'] = "$column$operator'$value'";
     
     return new static();
   }
@@ -328,13 +328,13 @@ class ModelMySQL {
   */
   public static function where_in($column,$arr, $in = true){
     foreach($arr as $index => $value){
-      $arr[$index] = self::db()->real_escape_string($value);
+      $arr[$index] = static::db()->real_escape_string($value);
     }
     
     if ($in)
-      self::$querySelect['where'] = "$column IN (".join(', ',$arr).")";
+      static::$querySelect['where'] = "$column IN (".join(', ',$arr).")";
     else
-      self::$querySelect['where'] = "$column NOT IN (".join(', ',$arr).")";
+      static::$querySelect['where'] = "$column NOT IN (".join(', ',$arr).")";
     
     return new static();
   }
@@ -355,8 +355,8 @@ class ModelMySQL {
   *   Columna a comparar para hacer el join.
   *
   * Sintaxis posibles: 
-  *  - self::leftJoin(tabla,columnaA, operador, columnB)
-  *  - self::leftJoin(tabla,columnaA, columnB) // Operador por defecto "="
+  *  - static::leftJoin(tabla,columnaA, operador, columnB)
+  *  - static::leftJoin(tabla,columnaA, columnB) // Operador por defecto "="
   */
   public static function leftJoin($table, $columnA, $operator, $columnB = null){
     if (is_null($columnB)){
@@ -364,11 +364,11 @@ class ModelMySQL {
       $operator = '=';
     }
     
-    $columnA = self::db()->real_escape_string($columnA);
-    $columnB = self::db()->real_escape_string($columnB);
+    $columnA = static::db()->real_escape_string($columnA);
+    $columnB = static::db()->real_escape_string($columnB);
     
-    self::$querySelect['leftJoin'] = $table;
-    self::$querySelect['on'] = "$columnA$operator$columnB";
+    static::$querySelect['leftJoin'] = $table;
+    static::$querySelect['on'] = "$columnA$operator$columnB";
     
     
     return new static();
@@ -390,8 +390,8 @@ class ModelMySQL {
   *   Columna a comparar para hacer el join.
   *
   * Sintaxis posibles: 
-  *  - self::rightJoin(tabla,columnaA, operador, columnB)
-  *  - self::rightJoin(tabla,columnaA, columnB) // Operador por defecto "="
+  *  - static::rightJoin(tabla,columnaA, operador, columnB)
+  *  - static::rightJoin(tabla,columnaA, columnB) // Operador por defecto "="
   */
   public static function rightJoin($table, $columnA, $operator, $columnB = null){
     if (is_null($columnB)){
@@ -399,11 +399,11 @@ class ModelMySQL {
       $operator = '=';
     }
     
-    $columnA = self::db()->real_escape_string($columnA);
-    $columnB = self::db()->real_escape_string($columnB);
+    $columnA = static::db()->real_escape_string($columnA);
+    $columnB = static::db()->real_escape_string($columnB);
     
-    self::$querySelect['rightJoin'] = $table;
-    self::$querySelect['on'] = "$columnA$operator$columnB";
+    static::$querySelect['rightJoin'] = $table;
+    static::$querySelect['on'] = "$columnA$operator$columnB";
     
     
     return new static();
@@ -422,9 +422,9 @@ class ModelMySQL {
   *   El valor el valor a comparar en la columna.
   *
   * Sintaxis posibles: 
-  *  - self::and(columna, operador, valor)
-  *  - self::and(columna, valor)  // Operador por defecto "="
-  *  - self::and(columna, valor)->and(columna, valor)->and(columna, valor) // anidado
+  *  - static::and(columna, operador, valor)
+  *  - static::and(columna, valor)  // Operador por defecto "="
+  *  - static::and(columna, valor)->and(columna, valor)->and(columna, valor) // anidado
   */
   public static function and($column, $operator, $value=null){
     if (is_null($value)){
@@ -432,9 +432,9 @@ class ModelMySQL {
       $operator = '=';
     }
     
-    $value = self::db()->real_escape_string($value);
+    $value = static::db()->real_escape_string($value);
     
-    self::$querySelect['AndOr'] .= " AND $column$operator'$value'";
+    static::$querySelect['AndOr'] .= " AND $column$operator'$value'";
     
     return new static();
   }
@@ -452,9 +452,9 @@ class ModelMySQL {
   *   El valor el valor a comparar en la columna.
   *
   * Sintaxis posibles: 
-  *  - self::or(columna, operador, valor)
-  *  - self::or(columna, valor)  // Operador por defecto "="
-  *  - self::or(columna, valor)->or(columna, valor)->or(columna, valor) // anidado
+  *  - static::or(columna, operador, valor)
+  *  - static::or(columna, valor)  // Operador por defecto "="
+  *  - static::or(columna, valor)->or(columna, valor)->or(columna, valor) // anidado
   */
   public static function or($column, $operator, $value=null){
     if (is_null($value)){
@@ -462,9 +462,9 @@ class ModelMySQL {
       $operator = '=';
     }
     
-    $value = self::db()->real_escape_string($value);
+    $value = static::db()->real_escape_string($value);
     
-    self::$querySelect['AndOr'] .= " OR $column$operator'$value'";
+    static::$querySelect['AndOr'] .= " OR $column$operator'$value'";
     
     return new static();
   }
@@ -476,7 +476,7 @@ class ModelMySQL {
   *   Columnas por las que se agrupará.
   */
   public static function groupBy($arr){
-    self::$querySelect['groupBy'] = join(', ', $arr);
+    static::$querySelect['groupBy'] = join(', ', $arr);
     return new static();
   }
   
@@ -485,9 +485,9 @@ class ModelMySQL {
     $final = (int)$final;
   
     if ($final==0)
-      self::$querySelect['limit'] = $initial;
+      static::$querySelect['limit'] = $initial;
     else
-      self::$querySelect['limit'] = $initial.', '.$final;
+      static::$querySelect['limit'] = $initial.', '.$final;
       
     return new static();
   }
@@ -504,16 +504,16 @@ class ModelMySQL {
   */
   public static function orderBy($value, $order = 'ASC'){
     if ($value == "RAND"){
-      self::$querySelect['orderBy'] = 'RAND()';
+      static::$querySelect['orderBy'] = 'RAND()';
       return new static();
     }
     
-    $value = self::db()->real_escape_string($value);
+    $value = static::db()->real_escape_string($value);
     
     if (!(strtoupper($order) == 'ASC' || strtoupper($order) == 'DESC'))
       $order = 'ASC';    
       
-    self::$querySelect['orderBy'] = $value.' '.$order;
+    static::$querySelect['orderBy'] = $value.' '.$order;
     
     return new static();
   }
@@ -524,9 +524,9 @@ class ModelMySQL {
   * @return int
   */
   public static function count(){
-    self::$querySelect['select'] = 'count(*) as quantity';
-    $sql = self::buildQuery();
-    $result = self::query($sql)->fetch_assoc();
+    static::$querySelect['select'] = 'count(*) as quantity';
+    $sql = static::buildQuery();
+    $result = static::query($sql)->fetch_assoc();
     return $result['quantity'];
   }
   
@@ -537,7 +537,7 @@ class ModelMySQL {
   * @return ModelMySQL
   */
   public static function getById($id){
-    return self::where('id', $id)->getFirst();
+    return static::where('id', $id)->getFirst();
   }
   
   /*
@@ -555,7 +555,7 @@ class ModelMySQL {
       $objAtts = array_keys((new $className())->getVars());
     }
     
-    $db = self::db();
+    $db = static::db();
     
     $search = $db->real_escape_string($search);
     
@@ -565,10 +565,10 @@ class ModelMySQL {
       $where[] = "$row LIKE '%$search%'";
     }
     
-    if (self::$querySelect['where']=='')
-      self::$querySelect['where'] = join($where, ' OR ');
+    if (static::$querySelect['where']=='')
+      static::$querySelect['where'] = join($where, ' OR ');
     else
-      self::$querySelect['where'] = self::$querySelect['where'] .' AND ('.join($where, ' OR ').')';
+      static::$querySelect['where'] = static::$querySelect['where'] .' AND ('.join($where, ' OR ').')';
     
     return new static();
   }
@@ -579,13 +579,13 @@ class ModelMySQL {
   * @return ModelMySQL[]
   */
   public static function get(){ // Devuelve array vacío si no encuentra nada
-    $sql = self::buildQuery();
-    $result = self::query($sql);
+    $sql = static::buildQuery();
+    $result = static::query($sql);
     
     $instaces = [];
     
     while ($row = $result->fetch_assoc()){
-      $instaces[] = self::getInstance($row);
+      $instaces[] = static::getInstance($row);
     }
                    
     return $instaces;
@@ -598,8 +598,8 @@ class ModelMySQL {
   *   Puede retornar un objeto ModelMySQL o null.
   */
   public static function getFirst(){ // Devuelve null si no encuentra nada
-    self::limit(1);
-    $instaces = self::get();
+    static::limit(1);
+    $instaces = static::get();
     return empty($instaces) ? null : $instaces[0];
   }
 
@@ -609,14 +609,14 @@ class ModelMySQL {
   * @return ModelMySQL[]
   */
   public static function all(){
-    $sql = 'SELECT * FROM '.self::table();
+    $sql = 'SELECT * FROM '.static::table();
     
-    $result = self::query($sql);
+    $result = static::query($sql);
     
     $instaces = [];
     
     while ($row = $result->fetch_assoc()){
-      $instaces[] = self::getInstance($row);
+      $instaces[] = static::getInstance($row);
     }
     
     return $instaces;