diff --git a/src/Common/EntityResolver.php b/src/Common/EntityResolver.php
index e006602..2d27d77 100644
--- a/src/Common/EntityResolver.php
+++ b/src/Common/EntityResolver.php
@@ -63,7 +63,7 @@ class EntityResolver {
                         break;
 
                         case static::KEY_COLUMN_NAME:
-                            $key = $tag['object']->name ?? $item['name'];
+                            $key = strtolower($tag['object']->name ?? $item['name']);
                         break;
 
                         default:
diff --git a/src/Common/PdoObject.php b/src/Common/PdoObject.php
index b874e7a..fa3c3c9 100644
--- a/src/Common/PdoObject.php
+++ b/src/Common/PdoObject.php
@@ -22,8 +22,8 @@ class PdoObject extends PDO {
         }
     }
 
-    public function runQuery(string $sql, array $parameters = []): PDOStatement {
-        # var_dump($sql, $parameters); die();
+    public function runQuery(string $sql, array $parameters = []): ? PDOStatement {
+        var_dump($sql, $parameters);die();
         
         try {
             if (false !== ( $statement = $this->prepare($sql) )) {
@@ -32,9 +32,11 @@ class PdoObject extends PDO {
         } catch (\PDOException $e) {
             throw $e;
         }
+        
+        return null;
     }
 
-    public function execute(PDOStatement $statement, array $parameters = [], bool $commit = true): ?PDOStatement {
+    public function execute(PDOStatement $statement, array $parameters = [], bool $commit = true): ? PDOStatement {
         try {
             if ( ! $this->inTransaction() ) {
                 $this->beginTransaction();
diff --git a/src/ConnectionAdapter.php b/src/ConnectionAdapter.php
index 83235a6..a4e6013 100644
--- a/src/ConnectionAdapter.php
+++ b/src/ConnectionAdapter.php
@@ -14,7 +14,7 @@ class ConnectionAdapter
 
     protected AdapterInterface $adapter;
 
-    public PdoObject $pdo;
+    protected PdoObject $pdo;
 
     public function __construct(string $name = "default", array $configuration = [], bool $default = false)
     {
@@ -54,6 +54,11 @@ class ConnectionAdapter
     {
         return $this->adapter;
     }
+    
+    public function pdo() : PdoObject
+    {
+        return $this->pdo ?? $this->pdo = $this->connect()->pdo;
+    }
 
     /**
      * Instanciate an adapter which interact with the data source
diff --git a/src/EntityCollection.php b/src/EntityCollection.php
index 1fdfcec..5c3ffe0 100644
--- a/src/EntityCollection.php
+++ b/src/EntityCollection.php
@@ -18,6 +18,17 @@ class EntityCollection extends \ArrayObject {
             }
         }
     }
+        
+    public function filtersCollection(Callable $callback) : self
+    {
+        $collection = new static();
+        
+        foreach($this->filters($callback) as $item) {
+            $collection->append($item);
+        }
+        
+        return $collection;
+    }
     
     public function searchOne($value, string $field) : object 
     {
@@ -53,4 +64,4 @@ class EntityCollection extends \ArrayObject {
         
         return $list;
     }
-}
\ No newline at end of file
+}
diff --git a/src/EntityTrait.php b/src/EntityTrait.php
index d68b20a..0c33a76 100644
--- a/src/EntityTrait.php
+++ b/src/EntityTrait.php
@@ -15,7 +15,7 @@ trait EntityTrait {
     /**
      * @Ignore
      */
-    protected bool $strictEntityFieldsDeclaration = true;
+    protected bool $strictEntityFieldsDeclaration = false;
     
     /**
      * @Ignore
@@ -80,6 +80,11 @@ trait EntityTrait {
         throw new \Exception(sprintf("[%s] - Undefined variable: %s", static::class, $name));
     }
     
+    public function __isset(string $name) : bool
+    {
+        return isset($this->$name);
+    }
+    
     /**
      * @Ignore
      */
diff --git a/src/Query/Join.php b/src/Query/Join.php
index c72de34..7420e70 100644
--- a/src/Query/Join.php
+++ b/src/Query/Join.php
@@ -11,18 +11,27 @@ class Join extends Fragment {
     const TYPE_CROSS = "CROSS";
     const TYPE_NATURAL = "NATURAL";
 
-    public string $type = self::TYPE_INNER;
-
     public bool $outer = false;
+    
+    public array $joins = [];
 
+    public function add(string $side, string $table, string $field, $value) 
+    {
+        $this->joins[] = [
+            'side' => $side,
+            'table' => $table,
+            'field' => $field,
+            'value' => $value,
+        ];
+    }
+    
     public function render() : string
     {
         return $this->renderSegments([
-            $this->side,
-            'JOIN',
-            /* table here! */,
-            'ON',
-            /* WHERE ! */
+            #'JOIN',
+            # table,
+            # 'ON',
+            # WHERE ! ,
         ]);
     }
 }
diff --git a/src/QueryBuilder.php b/src/QueryBuilder.php
index 0b271a1..42865b5 100644
--- a/src/QueryBuilder.php
+++ b/src/QueryBuilder.php
@@ -39,15 +39,15 @@ class QueryBuilder
     
     public function insert(array $fieldlist, string $table, ? string $alias = null, ? string $database = null, ? string $schema = null) : self
     {
-        if ( null === $this->getFragment(Query\Insert::class) ) {            
-            if ( $database ) {
-                $table = "\"$database\".$table";
-            }
-
+        if ( null === $this->getFragment(Query\Insert::class) ) {    
             if ( $schema ) {
                 $table = "\"$schema\".$table";
             }
 
+            if ( $database ) {
+                $table = "\"$database\".$table";
+            }
+            
             $insert = new Query\Insert();
             $this->push($insert);
             
@@ -73,14 +73,14 @@ class QueryBuilder
     
     public function update(string $table, ? string $alias = null, ? string $database = null, ? string $schema = null) : self
     {
-        if ( ! $this->getFragment(Query\Update::class) ) {            
-            if ( $database ) {
-                $table = "\"$database\".$table";
-            }
-
+        if ( ! $this->getFragment(Query\Update::class) ) {
             if ( $schema ) {
                 $table = "\"$schema\".$table";
             }
+            
+            if ( $database ) {
+                $table = "\"$database\".$table";
+            }
 
             $update = new Query\Update();
             $this->push($update);
@@ -95,7 +95,7 @@ class QueryBuilder
     public function set(array $dataset) : self 
     {
         
-        if ( null === ( $values = $this->getFragment(Query\Set::class) ) ) {
+        if ( null === ( $set = $this->getFragment(Query\Set::class) ) ) {
             $set = new Query\Set($this);
             $this->push($set);
         }
@@ -116,13 +116,13 @@ class QueryBuilder
 
     public function from(string $table, ? string $alias = null, ? string $database = null, ? string $schema = null) : self
     {
-        if ( $database ) {
-            $table = "$database.$table";
-        }
-        
         if ( $schema ) {
             $table = "\"$schema\".$table";
         }
+        
+        if ( $database ) {
+            $table = "$database.$table";
+        }
 
         if ( null !== ( $from = $this->getFragment(Query\From::class) ) ) {
             $from->add($alias ? [ $alias => $table ] : $table);
@@ -219,6 +219,28 @@ class QueryBuilder
         return $this;
     }
 
+    public function join(string $type, $table, $field, $value, bool $outer = false) : self
+    {
+        if ( null === $join = $this->getFragment(Query\Join::class) ) {
+            $join = new Query\Join();
+            $this->push($join);
+        }
+
+        $join->add($type, $table, $field, $value);
+        
+        $join->outer = $outer;
+        
+        return $this;
+    }
+    /*
+      "LEFT JOIN PAI_DOS ON PAI_DOS.MATR = PAI_DOS_EMPL.MATR"
+      "LEFT JOIN PAI_DOS_2 ON PAI_DOS_2.MATR = PAI_DOS.MATR"
+      "LEFT JOIN PAI_CAND ON PAI_CAND.MATR = PAI_DOS.MATR"
+    
+      "LEFT JOIN PAI_TAB_CORP_EMPL ON PAI_TAB_CORP_EMPL.CORP_EMPL = PAI_DOS_EMPL.CORP_EMPL",
+      "LEFT JOIN PAI_TAB_LIEU_TRAV ON PAI_TAB_LIEU_TRAV.LIEU_TRAV = PAI_DOS_EMPL.LIEU_TRAV",
+      "LEFT JOIN PAI_TAB_BAT ON PAI_TAB_BAT.BAT = PAI_TAB_LIEU_TRAV.BAT"
+    */
     public function push(Query\Fragment $queryFragment) : self
     {
         $this->queryStack[] = $queryFragment;
@@ -240,6 +262,15 @@ class QueryBuilder
 
         return implode(" ", $sql);
     }
+    
+    public function reset() : void
+    {
+        $this->parameters = $this->values = $this->queryStack = [];
+        $this->conditionOperator = Query\Where::CONDITION_AND;
+        $this->parameterIndex = 0;
+
+        unset($this->where);
+    }
 
     public function getFragment(string $class) : ? Query\Fragment
     {
diff --git a/src/Repository.php b/src/Repository.php
index 9975b94..cca915f 100644
--- a/src/Repository.php
+++ b/src/Repository.php
@@ -31,9 +31,14 @@ class Repository
         return $this->limit(1)->collectionFromQuery()[0] ?? null;
     }
 
+    public function loadOneFromField($field, $value) : ? object
+    {
+        return $this->where($field, $value)->loadOne();
+    }
+    
     public function loadFromPk($value, $primaryKey = "id") : ? object
     {
-        return $this->where($primaryKey, $value)->loadOne();
+        return $this->loadOneFromField($primaryKey, $value);
     }
     
     public function loadAll() : EntityCollection
@@ -99,24 +104,24 @@ class Repository
             if ( $primaryKeyDefinition === null ) {
                 throw new \Exception(sprintf("No primary key found for entity %s", $this->entityClass));
             }
-            
-            $pkField = key($primaryKeyDefinition);
-            $pkFieldName = $primaryKeyDefinition[$pkField]->name ?? $pkField;
-            $this->where($pkFieldName, $dataset[$pkFieldName]);
-            
+
             $diff = array_diff_assoc($dataset, $entity->entityGetDataset(true));
             
             if ( [] !== $diff ) {
+                $pkField = key($primaryKeyDefinition);
+                $pkFieldName = $primaryKeyDefinition[$pkField]->name ?? $pkField;
+                $this->where($pkFieldName, $dataset[$pkFieldName]);
+
                 $update = $this->updateSqlQuery($diff)->runQuery();
                 
-                return (bool) $update->rowCount();
-            }   
+                return $update ? (bool) $update->rowCount() : false;
+            }
         }
         
         return false;
     }
     
-    public function saveAll(EntityCollection $collection) : bool 
+    public function saveAll(EntityCollection $collection) : void 
     {
         foreach($collection as $entity) {
             $this->save($entity);
@@ -179,6 +184,8 @@ class Repository
 
     public function join(string $type, $table, $field, $value) : self
     {
+        $this->queryBuilder->join($type, $table, $field, $value);
+        
         return $this;
     }
 
@@ -370,7 +377,7 @@ class Repository
         return $entityCollection;
     }
 
-    public function runQuery() : \PDOStatement
+    public function runQuery() : ? \PDOStatement
     {
         $this->finalizeQuery();
         
diff --git a/src/Ulmus.php b/src/Ulmus.php
index d97bd9a..18396a4 100644
--- a/src/Ulmus.php
+++ b/src/Ulmus.php
@@ -21,14 +21,16 @@ abstract class Ulmus
     public static function iterateQueryBuilder(QueryBuilder $queryBuilder, ? ConnectionAdapter $adapter = null) : Generator
     {
         $sql = $queryBuilder->render();
-        $statement = ( $adapter ?: static::$defaultAdapter )->pdo->select($sql, $queryBuilder->parameters ?? []);
+        
+        $statement = ( $adapter ?: static::$defaultAdapter )->pdo()->select($sql, $queryBuilder->parameters ?? []);
 
         while ( $row = $statement->fetch() ) {
             yield $row;
         }
 
         $statement->closeCursor();
-
+        $queryBuilder->reset();
+        
         return [
             'count' => $statement->rowCount(),
         ];
@@ -36,12 +38,15 @@ abstract class Ulmus
     
     public static function pdo(? ConnectionAdapter $adapter = null) : Common\PdoObject
     {
-        return ( $adapter ?: static::$defaultAdapter )->pdo;
+        return ( $adapter ?: static::$defaultAdapter )->pdo();
     }
     
     public static function runQuery(QueryBuilder $queryBuilder, ? ConnectionAdapter $adapter = null)
     {
-        return static::pdo($adapter)->runQuery($queryBuilder->render(), array_merge($queryBuilder->values ?? [], $queryBuilder->parameters ?? []));
+        $result = static::pdo($adapter)->runQuery($queryBuilder->render(), array_merge($queryBuilder->values ?? [], $queryBuilder->parameters ?? []));
+        $queryBuilder->reset();
+        
+        return $result;
     }
 
     public static function resolveEntity(string $entityClass) : Common\EntityResolver
@@ -80,6 +85,9 @@ abstract class Ulmus
     
     protected static function fetchQueryBuilder(QueryBuilder $queryBuilder, ? ConnectionAdapter $adapter = null) : array
     {
-        return ( $adapter ?: static::$defaultAdapter )->pdo->select($queryBuilder->render(), $queryBuilder->parameters ?? [])->fetchAll();
+        $result =  ( $adapter ?: static::$defaultAdapter )->pdo->select($queryBuilder->render(), $queryBuilder->parameters ?? [])->fetchAll();
+        $queryBuilder->reset();
+        
+        return $result;
     }
 }