diff --git a/hook.php b/hook.php
index 59b4d006..7e02a022 100644
--- a/hook.php
+++ b/hook.php
@@ -256,15 +256,24 @@ function plugin_fields_rule_matched($params = [])
 
             if (isset($params['input']['plugin_fusioninventory_agents_id'])) {
                 foreach ($params['output'] as $field => $value) {
-                   // check if current field is in a tab container
-                    $query = "SELECT c.id
-                         FROM glpi_plugin_fields_fields f
-                         LEFT JOIN glpi_plugin_fields_containers c
-                            ON c.id = f.plugin_fields_containers_id
-                         WHERE f.name = '$field'";
-                    $res = $DB->query($query);
-                    if ($DB->numrows($res) > 0) {
-                        $data = $DB->fetchAssoc($res);
+                    // check if current field is in a tab container
+                    $iterator = $DB->request([
+                        'SELECT' => 'glpi_plugin_fields_containers.id',
+                        'FROM'   => 'glpi_plugin_fields_containers',
+                        'LEFT JOIN' => [
+                            'glpi_plugin_fields_fields' => [
+                                'FKEY' => [
+                                    'glpi_plugin_fields_containers' => 'id',
+                                    'glpi_plugin_fields_fields'     => 'plugin_fields_containers_id'
+                                ]
+                            ]
+                        ],
+                        'WHERE' => [
+                            'glpi_plugin_fields_fields.name' => $field,
+                        ]
+                    ]);
+                    if (count($iterator) > 0) {
+                        $data = $iterator->next();
 
                         //retrieve computer
                         $agents_id = $params['input']['plugin_fusioninventory_agents_id'];
diff --git a/inc/container.class.php b/inc/container.class.php
index 4f7769c8..0a18ea30 100644
--- a/inc/container.class.php
+++ b/inc/container.class.php
@@ -102,8 +102,20 @@ public static function installBaseData(Migration $migration, $version)
             $migration->changeField($table, 'itemtype', 'itemtypes', 'longtext');
             $migration->migrationOneTable($table);
 
-            $query = "UPDATE `$table` SET `itemtypes` = CONCAT('[\"', `itemtypes`, '\"]')";
-            $DB->query($query) or die($DB->error());
+            $DB->updateOrDie(
+                $table,
+                [
+                    'itemtypes' => new QueryExpression(
+                        sprintf(
+                            'CONCAT(%s, %s, %s)',
+                            $DB->quoteValue('[\"'),
+                            $DB->quoteName('itemtype'),
+                            $DB->quoteValue('\"]')
+                        )
+                    ),
+                ],
+                [1]
+            );
         }
 
         //add display preferences for this class
@@ -252,15 +264,36 @@ public static function installUserData(Migration $migration, $version)
                     $compfields = $fields->find(['plugin_fields_containers_id' => $comptab, 'name' => $newname]);
                     if ($compfields) {
                         $newname = $newname . '_os';
-                        $DB->query("UPDATE glpi_plugin_fields_fields SET name='$newname' WHERE name='{$field['name']}' AND plugin_fields_containers_id='$ostab'");
+                        $DB->update(
+                            'glpi_plugin_fields_fields',
+                            [
+                                'name' => $newname
+                            ],
+                            [
+                                'name' => $field['name'],
+                                'plugin_fields_containers_id' => $ostab
+                            ]
+                        );
                     }
                     $compdata::addField($newname, $field['type']);
                     $fieldnames[$field['name']] = $newname;
                 }
 
-                $sql = "UPDATE glpi_plugin_fields_fields SET plugin_fields_containers_id='$comptab' WHERE plugin_fields_containers_id='$ostab'";
-                $DB->query($sql);
-                $DB->query("DELETE FROM glpi_plugin_fields_containers WHERE id='$ostab'");
+                $DB->update(
+                    'glpi_plugin_fields_fields',
+                    [
+                        'plugin_fields_containers_id' => $comptab
+                    ],
+                    [
+                        'plugin_fields_containers_id' => $ostab
+                    ]
+                );
+                $DB->delete(
+                    'glpi_plugin_fields_containers',
+                    [
+                        'id' => $ostab
+                    ]
+                );
 
                 //migrate existing data
                 $existings = $osdata->find();
@@ -275,9 +308,16 @@ public static function installUserData(Migration $migration, $version)
                 //drop old table
                 $DB->query("DROP TABLE " . $osdata::getTable());
             } else {
-                $sql = "UPDATE glpi_plugin_fields_containers SET type='dom', subtype=NULL WHERE id='$ostab'";
-                $comptab = $ostab;
-                $DB->query($sql);
+                $DB->update(
+                    'glpi_plugin_fields_containers',
+                    [
+                        'type' => 'dom',
+                        'subtype' => null
+                    ],
+                    [
+                        'id' => $ostab
+                    ]
+                );
             }
         }
 
@@ -1017,15 +1057,25 @@ public static function getUsedItemtypes($type = 'all', $must_be_active = false)
     {
         global $DB;
         $itemtypes = [];
-        $where = $type == 'all' ? '1=1' : ('type = "' . $type . '"');
+        $where = [];
+
+        if ($type !== 'all') {
+            $where['type'] = $type;
+        }
+
         if ($must_be_active) {
-            $where .= ' AND is_active = 1';
+            $where['is_active'] = 1;
         }
 
-        $query = 'SELECT DISTINCT `itemtypes` FROM `glpi_plugin_fields_containers` WHERE ' . $where;
-        $result = $DB->query($query);
-        while (list($data) = $DB->fetchArray($result)) {
-            $jsonitemtype = json_decode($data);
+        $iterator = $DB->request([
+            'SELECT' => 'itemtypes',
+            'DISTINCT' => true,
+            'FROM' => self::getTable(),
+            'WHERE' => $where,
+        ]);
+
+        foreach ($iterator as $data) {
+            $jsonitemtype = json_decode($data['itemtypes']);
             $itemtypes    = array_merge($itemtypes, $jsonitemtype);
         }
 
@@ -1354,19 +1404,20 @@ public static function validateValues($data, $itemtype, $massiveaction)
             } else if ($field['mandatory'] == 1 && isset($data['items_id'])) {
                 $tablename = getTableForItemType(self::getClassname($itemtype, $container->fields['name']));
 
-                $query = "SELECT * FROM `$tablename` WHERE
-                    `itemtype`='$itemtype'
-                    AND `items_id`='{$data['items_id']}'
-                    AND `plugin_fields_containers_id`='{$data['plugin_fields_containers_id']}'";
-
-                $db_result = [];
-                if ($result = $DB->query($query)) {
-                    $db_result = $DB->fetchAssoc($result);
-                    if (isset($db_result['plugin_fields_' . $name . 'dropdowns_id'])) {
-                        $value = $db_result['plugin_fields_' . $name . 'dropdowns_id'];
-                    } else if (isset($db_result[$name])) {
-                        $value = $db_result[$name];
-                    }
+                $iterator = $DB->request([
+                    'FROM' => $tablename,
+                    'WHERE' => [
+                        'itemtype' => $itemtype,
+                        'items_id' => $data['items_id'],
+                        'plugin_fields_containers_id' => $data['plugin_fields_containers_id'],
+                    ],
+                ]);
+
+                $db_result = $iterator->next();
+                if (isset($db_result['plugin_fields_' . $name . 'dropdowns_id'])) {
+                    $value = $db_result['plugin_fields_' . $name . 'dropdowns_id'];
+                } else if (isset($db_result[$name])) {
+                    $value = $db_result[$name];
                 }
             } else {
                 if ($massiveaction) {
diff --git a/inc/field.class.php b/inc/field.class.php
index 378da533..5471a449 100644
--- a/inc/field.class.php
+++ b/inc/field.class.php
@@ -367,11 +367,16 @@ public function post_purgeItem()
         $old_container = $this->fields['plugin_fields_containers_id'];
         $old_ranking   = $this->fields['ranking'];
 
-        $query = "UPDATE $table SET
-                ranking = ranking-1
-                WHERE plugin_fields_containers_id = $old_container
-                AND ranking > $old_ranking";
-        $DB->query($query);
+        $D->update(
+            $table,
+            [
+                'ranking' => new QueryExpression($DB->quoteName('ranking') . ' - 1')
+            ],
+            [
+                'plugin_fields_containers_id' => $old_container,
+                'ranking'                     => ['>', $old_ranking]
+            ]
+        );
 
         return true;
     }
@@ -441,14 +446,18 @@ public function getNextRanking()
     {
         global $DB;
 
-        $sql = "SELECT max(`ranking`) AS `rank`
-              FROM `" . self::getTable() . "`
-              WHERE `plugin_fields_containers_id` = '" .
-                  $this->fields['plugin_fields_containers_id'] . "'";
-        $result = $DB->query($sql);
+        $iterator = $DB->request([
+            'SELECT' => new \QueryExpression(
+                'max(' . $DB->quoteName('ranking') . ') AS ' . $DB->quoteName('rank')
+            ),
+            'FROM'   => self::getTable(),
+            'WHERE'  => [
+                'plugin_fields_containers_id' => $this->fields['plugin_fields_containers_id']
+            ]
+        ]);
 
-        if ($DB->numrows($result) > 0) {
-            $data = $DB->fetchAssoc($result);
+        if (count($iterator) > 0) {
+            $data = $iterator->next();
             return $data["rank"] + 1;
         }
         return 0;
@@ -496,14 +505,14 @@ public function showSummary($container)
         $cID = $container->fields['id'];
 
         // Display existing Fields
-        $query  = "SELECT `id`, `label`
-                FROM `" . $this->getTable() . "`
-                WHERE `plugin_fields_containers_id` = '$cID'
-                ORDER BY `ranking` ASC";
-        $result = $DB->query($query);
+        $iterator = $DB->request([
+            'SELECT' => ['id', 'label'],
+            'FROM' => self::getTable(),
+            'WHERE' => ['plugin_fields_containers_id' => $cID],
+            'ORDER' => 'ranking ASC'
+        ]);
 
         $rand   = mt_rand();
-
         echo "<div id='viewField$cID$rand'></div>";
 
         $ajax_params = [
@@ -525,7 +534,7 @@ public function showSummary($container)
            "<a href='javascript:viewAddField$cID$rand();'>";
         echo __("Add a new field", "fields") . "</a></div><br>";
 
-        if ($DB->numrows($result) == 0) {
+        if (count($iterator) == 0) {
             echo "<table class='tab_cadre_fixe'><tr class='tab_bg_2'>";
             echo "<th class='b'>" . __("No field for this block", "fields") . "</th></tr></table>";
         } else {
@@ -548,7 +557,7 @@ public function showSummary($container)
 
             Session::initNavigateListItems('PluginFieldsField', __('Fields list'));
 
-            while ($data = $DB->fetchArray($result)) {
+            foreach ($iterator as $data) {
                 if ($this->getFromDB($data['id'])) {
                     echo "<tr class='tab_bg_2' style='cursor:pointer'>";
 
@@ -1154,20 +1163,39 @@ public static function showSingle($itemtype, $searchOption, $massiveaction = fal
         );
 
         //find field
-        $query = "SELECT fields.plugin_fields_containers_id, fields.is_readonly, fields.multiple, fields.default_value
-                FROM glpi_plugin_fields_fields fields
-                LEFT JOIN glpi_plugin_fields_containers containers
-                  ON containers.id = fields.plugin_fields_containers_id
-                  AND containers.itemtypes LIKE '%$itemtype%'
-               WHERE fields.name = '$cleaned_linkfield'";
-        $res = $DB->query($query);
-        if ($DB->numrows($res) == 0) {
+        $iterator = $DB->request([
+            'SELECT' => [
+                'fields.plugin_fields_containers_id',
+                'fields.is_readonly',
+                'fields.multiple',
+                'fields.default_value'
+            ],
+            'FROM' => self::getTable() . ' AS fields',
+            'LEFT JOIN' => [
+                'glpi_plugin_fields_containers AS containers' => [
+                    'FKEY' => [
+                        'containers' => 'id',
+                        'fields' => 'plugin_fields_containers_id',
+                        [
+                            'AND' => [
+                                'containers.itemtypes' => ['LIKE' => "%$itemtype%"]
+                            ]
+                        ]
+                    ]
+                ]
+            ],
+            'WHERE' => [
+                'fields.name' => $cleaned_linkfield
+            ],
+        ]);
+
+        if (count($iterator) == 0) {
             return false;
         }
 
-        $data = $DB->fetchAssoc($res);
+        $data = $iterator->next();
 
-        //display an hidden post field to store container id
+        //display a hidden post field to store container id
         echo Html::hidden('c_id', ['value' => $data['plugin_fields_containers_id']]);
 
         //prepare array for function prepareHtmlFields