diff --git a/model/SqlCriteria.php b/model/SqlCriteria.php
index 3c0649e..b5b9a4c 100644
--- a/model/SqlCriteria.php
+++ b/model/SqlCriteria.php
@@ -2,6 +2,20 @@
 
 class SqlCriteria
 {
+    const JOIN_TYPE_DEFAULT = 100;
+    const JOIN_TYPE_LEFT = 101;
+    const JOIN_TYPE_RIGHT = 102;
+    const JOIN_TYPE_INNER = 103;
+    const JOIN_TYPE_OUTER = 104;
+
+    private static $join_type_to_reserved_keyword = array(
+        self::JOIN_TYPE_DEFAULT => 'JOIN',
+        self::JOIN_TYPE_LEFT => 'LEFT JOIN',
+        self::JOIN_TYPE_RIGHT => 'RIGHT JOIN',
+        self::JOIN_TYPE_INNER => 'INNER JOIN',
+        self::JOIN_TYPE_OUTER => 'OUTER JOIN',
+    );
+
     private $select = array();
 
     private $distinct = '';
@@ -23,6 +37,8 @@ class SqlCriteria
 
     private $sql_expression_params = array();
 
+    private $sql_join_expressions = array();
+
     /**
      * @param $model SqlModel
      * @param $sql_expression string|null Sql expression with SELECT and FROM operators. If fetched, then SqlCriteria::select(), SqlCriteria::distinct() disabled for use.
@@ -40,14 +56,39 @@ class SqlCriteria
      */
     public function find()
     {
+        // preparing link expressions (if exists)
+        if ($this->sql_join_expressions) {
+            if (!$this->sql_expression) {
+                $select = $this->model->getDb()->selectExpr($this->select, $this->distinct);
+                $this->sql_expression = 'SELECT ' . $select . ' FROM :table';
+            }
+            $this->sql_expression .= ' ' . implode(' ', $this->sql_join_expressions);
+        }
         return $this->model->find($this->select, $this->distinct, $this->where, $this->order, $this->limit, null, $this->group_by, $this->sql_expression, $this->sql_expression_params);
     }
 
+    public function delete()
+    {
+        return $this->model->find('', '', $this->where, null, null, null, null, 'DELETE FROM :table', $this->sql_expression_params)->affectedRows();
+    }
+
     public function count()
     {
         return $this->model->find(new DbExpr('COUNT(*) as count'), '', $this->where, null, null, null, null, $this->sql_expression, $this->sql_expression_params)->fetchField('count');
     }
 
+    public function join($join_table_name, $join_field_name, $donor_table_name = null, $donor_field_name = null, $join_type = self::JOIN_TYPE_DEFAULT)
+    {
+        $donor_field_name = $donor_field_name ? : $join_field_name;
+        $donor_table_name = $donor_table_name ? : 'table';
+        $this->sql_join_expressions[] = self::$join_type_to_reserved_keyword[$join_type]
+            . ' :' . $join_table_name
+            . ' ON :' . $donor_table_name . '.' . $donor_field_name . '='
+            . ':' . $join_table_name . '.' . $join_field_name;
+        $this->sql_expression_params[$join_table_name] = new DbExpr($this->model->identify($join_table_name));
+        return $this;
+    }
+
     /**
      * @param $cond string|array Condition with "?" placeholder @ex 'field=?' or 'field=1' or array('field=?' => 1', 'field=1')
      * @param $value string|array|DbExpr|null Value. Array transformed to DbExpr(implode(',' Array)) All elements in the array mast be integer
@@ -140,17 +181,21 @@ class SqlCriteria
 
     /**
      * @param string|array $fields
+     * @param bool $convert_to_db_expression
      * @ex SqlCriteria::select('field')
      * @ex SqlCriteria->select(array('field1', 'field2'))
      * @ex SqlCriteria->select('field1,field2')
      * @return SqlCriteria
      */
-    public function select($fields)
+    public function select($fields, $convert_to_db_expression = false)
     {
         if (!is_array($fields)) {
             $fields = explode(',', $fields);
         }
         $fields = array_map(function($item){return trim($item);},$fields);
+        if ($convert_to_db_expression) {
+            $fields = array_map(function($item){return new DbExpr($item);},$fields);
+        }
         $this->select = array_merge($this->select,$fields);
         return $this;
     }
diff --git a/model/SqlModel.php b/model/SqlModel.php
index 7b5154a..181c4ab 100644
--- a/model/SqlModel.php
+++ b/model/SqlModel.php
@@ -33,6 +33,11 @@ abstract class SqlModel extends Model
         return $this->db->quote($value);
     }
 
+    public function getDb()
+    {
+        return $this->db;
+    }
+
     /**
      * @param int $id
      * @return object
@@ -209,7 +214,7 @@ abstract class SqlModel extends Model
         $group_by = $this->db->groupByExpr($group_by);
         $order = isset($order['sort']) ? $this->order($order, $order['sort']) : false;
         $limit = $this->db->limitExpr($limit);
-        $result_items = $this->fetchAll(
+        $result = $this->query(
             (($sql_expression) ? $sql_expression : ('SELECT ' . $select . ' FROM ' . $this->table()))
                 . (($where) ? (' WHERE ' . $where) : '')
                 . (($group_by) ? (' GROUP BY ' . $group_by) : '')
@@ -218,7 +223,7 @@ abstract class SqlModel extends Model
             $sql_expression_params,
             $cache_key
         );
-        return new SqlResultProvider($result_items);
+        return new SqlResultProvider($result);
     }
 
     /**
diff --git a/model/SqlResultCollection.php b/model/SqlResultCollection.php
new file mode 100644
index 0000000..0d8a74d
--- /dev/null
+++ b/model/SqlResultCollection.php
@@ -0,0 +1,19 @@
+<?php
+
+class SqlResultCollection extends ArrayIterator
+{
+    private $items;
+
+    public function __construct($items)
+    {
+        $this->items = $items;
+        foreach ($items as $item) {
+            parent::append($item);
+        }
+    }
+
+    public function fetchAll()
+    {
+        return $this->items;
+    }
+}
\ No newline at end of file
diff --git a/model/SqlResultProvider.php b/model/SqlResultProvider.php
index 0bae36f..cae4e77 100644
--- a/model/SqlResultProvider.php
+++ b/model/SqlResultProvider.php
@@ -5,23 +5,44 @@ class SqlResultProvider
     /**
      * @var array
      */
+    private $result;
+
+    /**
+     * @var array
+     * @desc my be changed in assoc method
+     */
     private $result_items;
 
+    /**
+     * @var array
+     */
     private $result_items_base;
 
     /**
-     * @param $result_items array
+     * @param $result DbStatement
      */
-    public function __construct($result_items)
+    public function __construct($result)
     {
-        $this->result_items = $result_items;
+        $this->result = $result;
     }
 
-    public function assoc($field, $assoc_as_array = false)
+    private function defineResultItems()
     {
         if (is_null($this->result_items_base)) {
-            $this->result_items_base = $this->result_items;
+            $this->result_items_base = $this->result->fetchAll();
+            $this->result_items = $this->result_items_base;
         }
+    }
+
+    /**
+     * @param $field string
+     * @param bool $assoc_as_array
+     * @return $this SqlResultProvider
+     * @throws ErrorException
+     */
+    public function assoc($field, $assoc_as_array = false)
+    {
+        $this->defineResultItems();
         $result_items_assoc = array();
         foreach ($this->result_items_base as $item) {
             if (!isset($item->{$field})) {
@@ -42,7 +63,7 @@ class SqlResultProvider
         // Ассоциирование внутри каждого элемента массива
         if ($assoc_as_array) {
             foreach ($result_items_assoc as &$value) {
-                $value = new SqlResultProvider($value);
+                $value = new SqlResultCollection($value);
             }
         }
         $this->result_items = $result_items_assoc;
@@ -51,18 +72,22 @@ class SqlResultProvider
 
     public function getKeys()
     {
-        return array_keys($this->result_items);
+        return array_keys($this->result);
     }
 
+    /**
+     * @return DbStatement[]|SqlResultCollection[]
+     */
     public function fetchAll()
     {
+        $this->defineResultItems();
         return $this->result_items;
     }
 
     /**
      * @param $key
      * @return mixed
-     * TODO: метод актуален только после вызова assoc
+     * метод актуален после вызова assoc
      */
     public function fetchKey($key)
     {
@@ -72,19 +97,19 @@ class SqlResultProvider
     /**
      * @param $field
      * @return mixed
-     * TODO: метод не актуален после вызова assoc с параметров assoc_as_array = true
      */
     public function fetchField($field)
     {
-        $item = current($this->result_items);
-        if ($item) {
-            return $item->{$field};
-        }
-        return false;
+        return $this->result->fetchField($field);
+    }
+
+    public function fetch($style = Db::FETCH_OBJ)
+    {
+        return $this->result->fetch($style);
     }
 
-    public function fetch()
+    public function affectedRows()
     {
-        return current($this->result_items);
+        return $this->result->affectedRows();
     }
 }
\ No newline at end of file