diff --git a/db_designer.php b/db_designer.php
index caa8e3a68b..c555dec1d1 100644
--- a/db_designer.php
+++ b/db_designer.php
@@ -15,8 +15,8 @@ require_once 'libraries/common.inc.php';
 
 $response = Response::getInstance();
 
-$databaseDesigner = new Designer();
-$designerCommon = new Common();
+$databaseDesigner = new Designer($GLOBALS['dbi']);
+$designerCommon = new Common($GLOBALS['dbi']);
 
 if (isset($_REQUEST['dialog'])) {
 
diff --git a/db_qbe.php b/db_qbe.php
index 94ea207133..a3359065c9 100644
--- a/db_qbe.php
+++ b/db_qbe.php
@@ -138,7 +138,7 @@ if ($message_to_display) {
 unset($message_to_display);
 
 // create new qbe search instance
-$db_qbe = new Qbe($GLOBALS['db'], $savedSearchList, $savedSearch);
+$db_qbe = new Qbe($GLOBALS['dbi'], $GLOBALS['db'], $savedSearchList, $savedSearch);
 
 $url = 'db_designer.php' . Url::getCommon(
     array_merge(
diff --git a/db_search.php b/db_search.php
index 5c611a50d4..e0ab1d0e08 100644
--- a/db_search.php
+++ b/db_search.php
@@ -37,7 +37,7 @@ $url_query .= '&goto=db_search.php';
 $url_params['goto'] = 'db_search.php';
 
 // Create a database search instance
-$db_search = new Search($GLOBALS['db']);
+$db_search = new Search($GLOBALS['dbi'], $GLOBALS['db']);
 
 // Display top links if we are not in an Ajax request
 if (! $response->isAjax()) {
diff --git a/libraries/classes/Database/Designer.php b/libraries/classes/Database/Designer.php
index c0cec8f68c..eab6605a7e 100644
--- a/libraries/classes/Database/Designer.php
+++ b/libraries/classes/Database/Designer.php
@@ -24,16 +24,24 @@ use PhpMyAdmin\Util;
  */
 class Designer
 {
+    /**
+     * @var DatabaseInterface
+     */
+    private $dbi;
+
     /**
      * @var Relation $relation
      */
     private $relation;
 
     /**
-     * Constructor
+     * Designer constructor.
+     *
+     * @param DatabaseInterface $dbi DatabaseInterface object
      */
-    public function __construct()
+    public function __construct(DatabaseInterface $dbi)
     {
+        $this->dbi = $dbi;
         $this->relation = new Relation();
     }
 
@@ -86,7 +94,7 @@ class Designer
         $page_query = "SELECT `page_nr`, `page_descr` FROM "
             . Util::backquote($cfgRelation['db']) . "."
             . Util::backquote($cfgRelation['pdf_pages'])
-            . " WHERE db_name = '" . $GLOBALS['dbi']->escapeString($db) . "'"
+            . " WHERE db_name = '" . $this->dbi->escapeString($db) . "'"
             . " ORDER BY `page_descr`";
         $page_rs = $this->relation->queryAsControlUser(
             $page_query,
@@ -95,7 +103,7 @@ class Designer
         );
 
         $result = [];
-        while ($curr_page = $GLOBALS['dbi']->fetchAssoc($page_rs)) {
+        while ($curr_page = $this->dbi->fetchAssoc($page_rs)) {
             $result[intval($curr_page['page_nr'])] = $curr_page['page_descr'];
         }
         return $result;
@@ -202,7 +210,7 @@ class Designer
                 . ' WHERE ' . Util::backquote('username') . ' = "'
                 . $GLOBALS['cfg']['Server']['user'] . '";';
 
-            $result = $GLOBALS['dbi']->fetchSingleRow($query);
+            $result = $this->dbi->fetchSingleRow($query);
 
             $params = json_decode($result['settings_data'], true);
         }
diff --git a/libraries/classes/Database/Designer/Common.php b/libraries/classes/Database/Designer/Common.php
index 51903ce0a1..12a3a3bf9b 100644
--- a/libraries/classes/Database/Designer/Common.php
+++ b/libraries/classes/Database/Designer/Common.php
@@ -28,10 +28,18 @@ class Common
     private $relation;
 
     /**
-     * Constructor
+     * @var \PhpMyAdmin\DatabaseInterface
      */
-    public function __construct()
+    private $dbi;
+
+    /**
+     * Common constructor.
+     *
+     * @param DatabaseInterface $dbi DatabaseInterface object
+     */
+    public function __construct(DatabaseInterface $dbi)
     {
+        $this->dbi = $dbi;
         $this->relation = new Relation();
     }
 
@@ -48,9 +56,9 @@ class Common
         $GLOBALS['designer']['OWNER'] = array();
         $GLOBALS['designer']['TABLE_NAME_SMALL'] = array();
 
-        $tables = $GLOBALS['dbi']->getTablesFull($GLOBALS['db']);
+        $tables = $this->dbi->getTablesFull($GLOBALS['db']);
         // seems to be needed later
-        $GLOBALS['dbi']->selectDb($GLOBALS['db']);
+        $this->dbi->selectDb($GLOBALS['db']);
         $i = 0;
         foreach ($tables as $one_table) {
             $GLOBALS['designer']['TABLE_NAME'][$i]
@@ -98,11 +106,11 @@ class Common
      */
     public function getColumnsInfo()
     {
-        $GLOBALS['dbi']->selectDb($GLOBALS['db']);
+        $this->dbi->selectDb($GLOBALS['db']);
         $tab_column = array();
         for ($i = 0, $cnt = count($GLOBALS['designer']["TABLE_NAME"]); $i < $cnt; $i++) {
-            $fields_rs = $GLOBALS['dbi']->query(
-                $GLOBALS['dbi']->getColumnsSql(
+            $fields_rs = $this->dbi->query(
+                $this->dbi->getColumnsSql(
                     $GLOBALS['db'],
                     $GLOBALS['designer_url']["TABLE_NAME_SMALL"][$i],
                     null,
@@ -113,7 +121,7 @@ class Common
             );
             $tbl_name_i = $GLOBALS['designer']['TABLE_NAME'][$i];
             $j = 0;
-            while ($row = $GLOBALS['dbi']->fetchAssoc($fields_rs)) {
+            while ($row = $this->dbi->fetchAssoc($fields_rs)) {
                 $tab_column[$tbl_name_i]['COLUMN_ID'][$j]   = $j;
                 $tab_column[$tbl_name_i]['COLUMN_NAME'][$j] = $row['Field'];
                 $tab_column[$tbl_name_i]['TYPE'][$j]        = $row['Type'];
@@ -131,16 +139,16 @@ class Common
      */
     public function getScriptContr()
     {
-        $GLOBALS['dbi']->selectDb($GLOBALS['db']);
+        $this->dbi->selectDb($GLOBALS['db']);
         $con = array();
         $con["C_NAME"] = array();
         $i = 0;
-        $alltab_rs = $GLOBALS['dbi']->query(
+        $alltab_rs = $this->dbi->query(
             'SHOW TABLES FROM ' . Util::backquote($GLOBALS['db']),
             DatabaseInterface::CONNECT_USER,
             DatabaseInterface::QUERY_STORE
         );
-        while ($val = @$GLOBALS['dbi']->fetchRow($alltab_rs)) {
+        while ($val = @$this->dbi->fetchRow($alltab_rs)) {
             $row = $this->relation->getForeigners($GLOBALS['db'], $val[0], '', 'internal');
 
             if ($row !== false) {
@@ -280,7 +288,7 @@ class Common
                 . "." . Util::backquote($cfgRelation['table_coords']) . "
             WHERE pdf_page_number = " . intval($pg);
 
-        $tab_pos = $GLOBALS['dbi']->fetchResult(
+        $tab_pos = $this->dbi->fetchResult(
             $query,
             'name',
             null,
@@ -308,7 +316,7 @@ class Common
             . " FROM " . Util::backquote($cfgRelation['db'])
             . "." . Util::backquote($cfgRelation['pdf_pages'])
             . " WHERE " . Util::backquote('page_nr') . " = " . intval($pg);
-        $page_name = $GLOBALS['dbi']->fetchResult(
+        $page_name = $this->dbi->fetchResult(
             $query,
             null,
             null,
@@ -369,10 +377,10 @@ class Common
         $query = "SELECT `page_nr`"
             . " FROM " . Util::backquote($cfgRelation['db'])
             . "." . Util::backquote($cfgRelation['pdf_pages'])
-            . " WHERE `db_name` = '" . $GLOBALS['dbi']->escapeString($db) . "'"
-            . " AND `page_descr` = '" .  $GLOBALS['dbi']->escapeString($db) . "'";
+            . " WHERE `db_name` = '" . $this->dbi->escapeString($db) . "'"
+            . " AND `page_descr` = '" .  $this->dbi->escapeString($db) . "'";
 
-        $default_page_no = $GLOBALS['dbi']->fetchResult(
+        $default_page_no = $this->dbi->fetchResult(
             $query,
             null,
             null,
@@ -410,9 +418,9 @@ class Common
             $query = "SELECT MIN(`page_nr`)"
                 . " FROM " . Util::backquote($cfgRelation['db'])
                 . "." . Util::backquote($cfgRelation['pdf_pages'])
-                . " WHERE `db_name` = '" . $GLOBALS['dbi']->escapeString($db) . "'";
+                . " WHERE `db_name` = '" . $this->dbi->escapeString($db) . "'";
 
-            $min_page_no = $GLOBALS['dbi']->fetchResult(
+            $min_page_no = $this->dbi->fetchResult(
                 $query,
                 null,
                 null,
@@ -467,9 +475,9 @@ class Common
             . "." . Util::backquote(
                 $GLOBALS['cfgRelation']['table_coords']
             )
-            . " WHERE `db_name` = '" . $GLOBALS['dbi']->escapeString($_REQUEST['db'])
+            . " WHERE `db_name` = '" . $this->dbi->escapeString($_REQUEST['db'])
             . "'"
-            . " AND `pdf_page_number` = '" . $GLOBALS['dbi']->escapeString($pg)
+            . " AND `pdf_page_number` = '" . $this->dbi->escapeString($pg)
             . "'";
 
         $res = $this->relation->queryAsControlUser(
@@ -493,11 +501,11 @@ class Common
                 . Util::backquote($GLOBALS['cfgRelation']['table_coords'])
                 . " (`db_name`, `table_name`, `pdf_page_number`, `x`, `y`)"
                 . " VALUES ("
-                . "'" . $GLOBALS['dbi']->escapeString($DB) . "', "
-                . "'" . $GLOBALS['dbi']->escapeString($TAB) . "', "
-                . "'" . $GLOBALS['dbi']->escapeString($pg) . "', "
-                . "'" . $GLOBALS['dbi']->escapeString($_REQUEST['t_x'][$key]) . "', "
-                . "'" . $GLOBALS['dbi']->escapeString($_REQUEST['t_y'][$key]) . "')";
+                . "'" . $this->dbi->escapeString($DB) . "', "
+                . "'" . $this->dbi->escapeString($TAB) . "', "
+                . "'" . $this->dbi->escapeString($pg) . "', "
+                . "'" . $this->dbi->escapeString($_REQUEST['t_x'][$key]) . "', "
+                . "'" . $this->dbi->escapeString($_REQUEST['t_y'][$key]) . "')";
 
             $res = $this->relation->queryAsControlUser(
                 $query,  true, DatabaseInterface::QUERY_STORE
@@ -523,7 +531,7 @@ class Common
             return false;
         }
 
-        $upd_query = new Table($table, $db, $GLOBALS['dbi']);
+        $upd_query = new Table($table, $db, $this->dbi);
         $upd_query->updateDisplayField($field, $cfgRelation);
 
         return true;
@@ -546,9 +554,9 @@ class Common
      */
     public function addNewRelation($db, $T1, $F1, $T2, $F2, $on_delete, $on_update, $DB1, $DB2)
     {
-        $tables = $GLOBALS['dbi']->getTablesFull($DB1, $T1);
+        $tables = $this->dbi->getTablesFull($DB1, $T1);
         $type_T1 = mb_strtoupper($tables[$T1]['ENGINE']);
-        $tables = $GLOBALS['dbi']->getTablesFull($DB2, $T2);
+        $tables = $this->dbi->getTablesFull($DB2, $T2);
         $type_T2 = mb_strtoupper($tables[$T2]['ENGINE']);
 
         // native foreign key
@@ -567,28 +575,28 @@ class Common
             // note: in InnoDB, the index does not requires to be on a PRIMARY
             // or UNIQUE key
             // improve: check all other requirements for InnoDB relations
-            $result = $GLOBALS['dbi']->query(
+            $result = $this->dbi->query(
                 'SHOW INDEX FROM ' . Util::backquote($DB1)
                 . '.' . Util::backquote($T1) . ';'
             );
 
             // will be use to emphasis prim. keys in the table view
             $index_array1 = array();
-            while ($row = $GLOBALS['dbi']->fetchAssoc($result)) {
+            while ($row = $this->dbi->fetchAssoc($result)) {
                 $index_array1[$row['Column_name']] = 1;
             }
-            $GLOBALS['dbi']->freeResult($result);
+            $this->dbi->freeResult($result);
 
-            $result = $GLOBALS['dbi']->query(
+            $result = $this->dbi->query(
                 'SHOW INDEX FROM ' . Util::backquote($DB2)
                 . '.' . Util::backquote($T2) . ';'
             );
             // will be used to emphasis prim. keys in the table view
             $index_array2 = array();
-            while ($row = $GLOBALS['dbi']->fetchAssoc($result)) {
+            while ($row = $this->dbi->fetchAssoc($result)) {
                 $index_array2[$row['Column_name']] = 1;
             }
-            $GLOBALS['dbi']->freeResult($result);
+            $this->dbi->freeResult($result);
 
             if (! empty($index_array1[$F1]) && ! empty($index_array2[$F2])) {
                 $upd_query  = 'ALTER TABLE ' . Util::backquote($DB2)
@@ -607,11 +615,11 @@ class Common
                     $upd_query   .= ' ON UPDATE ' . $on_update;
                 }
                 $upd_query .= ';';
-                if ($GLOBALS['dbi']->tryQuery($upd_query)) {
+                if ($this->dbi->tryQuery($upd_query)) {
                     return array(true, __('FOREIGN KEY relationship has been added.'));
                 }
 
-                $error = $GLOBALS['dbi']->getError();
+                $error = $this->dbi->getError();
                 return array(
                     false,
                     __('Error: FOREIGN KEY relationship could not be added!')
@@ -637,19 +645,19 @@ class Common
             . "(master_db, master_table, master_field, "
             . "foreign_db, foreign_table, foreign_field)"
             . " values("
-            . "'" . $GLOBALS['dbi']->escapeString($DB2) . "', "
-            . "'" . $GLOBALS['dbi']->escapeString($T2) . "', "
-            . "'" . $GLOBALS['dbi']->escapeString($F2) . "', "
-            . "'" . $GLOBALS['dbi']->escapeString($DB1) . "', "
-            . "'" . $GLOBALS['dbi']->escapeString($T1) . "', "
-            . "'" . $GLOBALS['dbi']->escapeString($F1) . "')";
+            . "'" . $this->dbi->escapeString($DB2) . "', "
+            . "'" . $this->dbi->escapeString($T2) . "', "
+            . "'" . $this->dbi->escapeString($F2) . "', "
+            . "'" . $this->dbi->escapeString($DB1) . "', "
+            . "'" . $this->dbi->escapeString($T1) . "', "
+            . "'" . $this->dbi->escapeString($F1) . "')";
 
         if ($this->relation->queryAsControlUser($q, false, DatabaseInterface::QUERY_STORE)
         ) {
             return array(true, __('Internal relationship has been added.'));
         }
 
-        $error = $GLOBALS['dbi']->getError(DatabaseInterface::CONNECT_CONTROL);
+        $error = $this->dbi->getError(DatabaseInterface::CONNECT_CONTROL);
         return array(
             false,
             __('Error: Internal relationship could not be added!')
@@ -672,9 +680,9 @@ class Common
         list($DB1, $T1) = explode(".", $T1);
         list($DB2, $T2) = explode(".", $T2);
 
-        $tables = $GLOBALS['dbi']->getTablesFull($DB1, $T1);
+        $tables = $this->dbi->getTablesFull($DB1, $T1);
         $type_T1 = mb_strtoupper($tables[$T1]['ENGINE']);
-        $tables = $GLOBALS['dbi']->getTablesFull($DB2, $T2);
+        $tables = $this->dbi->getTablesFull($DB2, $T2);
         $type_T2 = mb_strtoupper($tables[$T2]['ENGINE']);
 
         if (Util::isForeignKeySupported($type_T1)
@@ -689,11 +697,11 @@ class Common
                 $upd_query = 'ALTER TABLE ' . Util::backquote($DB2)
                     . '.' . Util::backquote($T2) . ' DROP FOREIGN KEY '
                     . Util::backquote($foreigner['constraint']) . ';';
-                if ($GLOBALS['dbi']->query($upd_query)) {
+                if ($this->dbi->query($upd_query)) {
                     return array(true, __('FOREIGN KEY relationship has been removed.'));
                 }
 
-                $error = $GLOBALS['dbi']->getError();
+                $error = $this->dbi->getError();
                 return array(
                     false,
                     __('Error: FOREIGN KEY relationship could not be removed!')
@@ -706,12 +714,12 @@ class Common
         $delete_query = "DELETE FROM "
             . Util::backquote($GLOBALS['cfgRelation']['db']) . "."
             . $GLOBALS['cfgRelation']['relation'] . " WHERE "
-            . "master_db = '" . $GLOBALS['dbi']->escapeString($DB2) . "'"
-            . " AND master_table = '" . $GLOBALS['dbi']->escapeString($T2) . "'"
-            . " AND master_field = '" . $GLOBALS['dbi']->escapeString($F2) . "'"
-            . " AND foreign_db = '" . $GLOBALS['dbi']->escapeString($DB1) . "'"
-            . " AND foreign_table = '" . $GLOBALS['dbi']->escapeString($T1) . "'"
-            . " AND foreign_field = '" . $GLOBALS['dbi']->escapeString($F1) . "'";
+            . "master_db = '" . $this->dbi->escapeString($DB2) . "'"
+            . " AND master_table = '" . $this->dbi->escapeString($T2) . "'"
+            . " AND master_field = '" . $this->dbi->escapeString($F2) . "'"
+            . " AND foreign_db = '" . $this->dbi->escapeString($DB1) . "'"
+            . " AND foreign_table = '" . $this->dbi->escapeString($T1) . "'"
+            . " AND foreign_field = '" . $this->dbi->escapeString($F1) . "'";
 
         $result = $this->relation->queryAsControlUser(
             $delete_query,
@@ -720,7 +728,7 @@ class Common
         );
 
         if (!$result) {
-            $error = $GLOBALS['dbi']->getError(DatabaseInterface::CONNECT_CONTROL);
+            $error = $this->dbi->getError(DatabaseInterface::CONNECT_CONTROL);
             return array(
                 false,
                 __('Error: Internal relationship could not be removed!') . "<br/>" . $error
@@ -754,9 +762,9 @@ class Common
                 . " FROM " . Util::backquote($cfgDesigner['db'])
                 . "." . Util::backquote($cfgDesigner['table'])
                 . " WHERE username = '"
-                . $GLOBALS['dbi']->escapeString($cfgDesigner['user']) . "';";
+                . $this->dbi->escapeString($cfgDesigner['user']) . "';";
 
-            $orig_data = $GLOBALS['dbi']->fetchSingleRow(
+            $orig_data = $this->dbi->fetchSingleRow(
                 $orig_data_query, 'ASSOC', DatabaseInterface::CONNECT_CONTROL
             );
 
@@ -770,7 +778,7 @@ class Common
                     . "." . Util::backquote($cfgDesigner['table'])
                     . " SET settings_data = '" . $orig_data . "'"
                     . " WHERE username = '"
-                    . $GLOBALS['dbi']->escapeString($cfgDesigner['user']) . "';";
+                    . $this->dbi->escapeString($cfgDesigner['user']) . "';";
 
                 $success = $this->relation->queryAsControlUser($save_query);
             } else {
diff --git a/libraries/classes/Database/Qbe.php b/libraries/classes/Database/Qbe.php
index 7c03cb5019..07fd9d0e87 100644
--- a/libraries/classes/Database/Qbe.php
+++ b/libraries/classes/Database/Qbe.php
@@ -11,6 +11,7 @@ namespace PhpMyAdmin\Database;
 
 use PhpMyAdmin\Core;
 use PhpMyAdmin\DatabaseInterface;
+use PhpMyAdmin\Message;
 use PhpMyAdmin\Relation;
 use PhpMyAdmin\Table;
 use PhpMyAdmin\Template;
@@ -219,14 +220,21 @@ class Qbe
      */
     private $relation;
 
+    /**
+     * @var DatabaseInterface
+     */
+    public $dbi;
+
     /**
      * Public Constructor
      *
-     * @param string        $dbname          Database name
-     * @param array         $savedSearchList List of saved searches
-     * @param SavedSearches $currentSearch   Current search id
+     * @param DatabaseInterface $dbi             DatabaseInterface object
+     * @param string            $dbname          Database name
+     * @param array             $savedSearchList List of saved searches
+     * @param SavedSearches     $currentSearch   Current search id
      */
     public function __construct(
+        $dbi,
         $dbname,
         array $savedSearchList = array(),
         $currentSearch = null
@@ -234,11 +242,13 @@ class Qbe
         $this->_db = $dbname;
         $this->_savedSearchList = $savedSearchList;
         $this->_currentSearch = $currentSearch;
+        $this->relation = new Relation();
+        $this->dbi = $dbi;
+
         $this->_loadCriterias();
         // Sets criteria parameters
         $this->_setSearchParams();
         $this->_setCriteriaTablesAndColumns();
-        $this->relation = new Relation();
     }
 
     /**
@@ -332,19 +342,19 @@ class Qbe
                 $this->_criteriaTables[$each_table] = ' selected="selected"';
             }
         } // end if
-        $all_tables = $GLOBALS['dbi']->query(
+        $all_tables = $this->dbi->query(
             'SHOW TABLES FROM ' . Util::backquote($this->_db) . ';',
             DatabaseInterface::CONNECT_USER,
             DatabaseInterface::QUERY_STORE
         );
-        $all_tables_count = $GLOBALS['dbi']->numRows($all_tables);
+        $all_tables_count = $this->dbi->numRows($all_tables);
         if (0 == $all_tables_count) {
             Message::error(__('No tables found in database.'))->display();
             exit;
         }
         // The tables list gets from MySQL
-        while (list($table) = $GLOBALS['dbi']->fetchRow($all_tables)) {
-            $columns = $GLOBALS['dbi']->getColumns($this->_db, $table);
+        while (list($table) = $this->dbi->fetchRow($all_tables)) {
+            $columns = $this->dbi->getColumns($this->_db, $table);
 
             if (empty($this->_criteriaTables[$table])
                 && ! empty($_REQUEST['TableList'])
@@ -370,7 +380,7 @@ class Qbe
                 } // end foreach
             } // end if
         } // end while
-        $GLOBALS['dbi']->freeResult($all_tables);
+        $this->dbi->freeResult($all_tables);
 
         // sets the largest width found
         $this->_realwidth = $this->_form_column_width . 'ex';
@@ -1286,7 +1296,7 @@ class Qbe
         $index_columns = array();
 
         foreach ($search_tables as $table) {
-            $indexes = $GLOBALS['dbi']->getTableIndexes($this->_db, $table);
+            $indexes = $this->dbi->getTableIndexes($this->_db, $table);
             foreach ($indexes as $index) {
                 $column = $table . '.' . $index['Column_name'];
                 if (isset($search_columns[$column])) {
@@ -1325,7 +1335,7 @@ class Qbe
     private function _getLeftJoinColumnCandidates(array $search_tables, array $search_columns,
         array $where_clause_columns
     ) {
-        $GLOBALS['dbi']->selectDb($this->_db);
+        $this->dbi->selectDb($this->_db);
 
         // Get unique columns and index columns
         $indexes = $this->_getIndexes(
diff --git a/libraries/classes/Database/Search.php b/libraries/classes/Database/Search.php
index 903dbed300..fa2f17fe78 100644
--- a/libraries/classes/Database/Search.php
+++ b/libraries/classes/Database/Search.php
@@ -9,6 +9,7 @@ declare(strict_types=1);
 
 namespace PhpMyAdmin\Database;
 
+use PhpMyAdmin\DatabaseInterface;
 use PhpMyAdmin\Template;
 use PhpMyAdmin\Util;
 
@@ -83,14 +84,21 @@ class Search
      */
     private $criteriaColumnName;
 
+    /**
+     * @var DatabaseInterface
+     */
+    private $dbi;
+
     /**
      * Public Constructor
      *
-     * @param string $db Database name
+     * @param DatabaseInterface $dbi DatabaseInterface object
+     * @param string            $db  Database name
      */
-    public function __construct($db)
+    public function __construct(DatabaseInterface $dbi, $db)
     {
         $this->db = $db;
+        $this->dbi = $dbi;
         $this->searchTypes = array(
             '1' => __('at least one of the words'),
             '2' => __('all of the words'),
@@ -109,7 +117,7 @@ class Search
      */
     private function setSearchParams()
     {
-        $this->tablesNamesOnly = $GLOBALS['dbi']->getTables($this->db);
+        $this->tablesNamesOnly = $this->dbi->getTables($this->db);
 
         if (empty($_REQUEST['criteriaSearchType'])
             || ! is_string($_REQUEST['criteriaSearchType'])
@@ -151,7 +159,7 @@ class Search
         ) {
             unset($this->criteriaColumnName);
         } else {
-            $this->criteriaColumnName = $GLOBALS['dbi']->escapeString(
+            $this->criteriaColumnName = $this->dbi->escapeString(
                 $_REQUEST['criteriaColumnName']
             );
         }
@@ -207,7 +215,7 @@ class Search
     private function getWhereClause($table)
     {
         // Columns to select
-        $allColumns = $GLOBALS['dbi']->getColumns($GLOBALS['db'], $table);
+        $allColumns = $this->dbi->getColumns($GLOBALS['db'], $table);
         $likeClauses = array();
         // Based on search type, decide like/regex & '%'/''
         $like_or_regex   = (($this->criteriaSearchType == 5) ? 'REGEXP' : 'LIKE');
@@ -215,7 +223,7 @@ class Search
         // For "as regular expression" (search option 5), LIKE won't be used
         // Usage example: If user is searching for a literal $ in a regexp search,
         // he should enter \$ as the value.
-        $criteriaSearchStringEscaped = $GLOBALS['dbi']->escapeString(
+        $criteriaSearchStringEscaped = $this->dbi->escapeString(
             $this->criteriaSearchString
         );
         // Extract search words or pattern
@@ -275,7 +283,7 @@ class Search
             // Gets the SQL statements
             $newSearchSqls = $this->getSearchSqls($eachTable);
             // Executes the "COUNT" statement
-            $resultCount = intval($GLOBALS['dbi']->fetchValue(
+            $resultCount = intval($this->dbi->fetchValue(
                 $newSearchSqls['select_count']
             ));
             $resultTotal += $resultCount;
diff --git a/libraries/classes/Dbi/DbiDummy.php b/libraries/classes/Dbi/DbiDummy.php
index 2614b26a0f..f45dddcf01 100644
--- a/libraries/classes/Dbi/DbiDummy.php
+++ b/libraries/classes/Dbi/DbiDummy.php
@@ -127,7 +127,7 @@ class DbiDummy implements DbiExtension
     public function fetchAny($result)
     {
         $query_data = &$this->getQueryData($result);
-        if ($query_data['pos'] >= count($query_data['result'])) {
+        if ($query_data['pos'] >= count((array) $query_data['result'])) {
             return false;
         }
         $ret = $query_data['result'][$query_data['pos']];
diff --git a/test/classes/Database/Designer/CommonTest.php b/test/classes/Database/Designer/CommonTest.php
index 75c919ea23..bf802a62e6 100644
--- a/test/classes/Database/Designer/CommonTest.php
+++ b/test/classes/Database/Designer/CommonTest.php
@@ -44,7 +44,6 @@ class CommonTest extends TestCase
                 )
             )
         );
-        $this->designerCommon = new Common();
     }
 
     /**
@@ -80,6 +79,8 @@ class CommonTest extends TestCase
             );
         $GLOBALS['dbi'] = $dbi;
 
+        $this->designerCommon = new Common($GLOBALS['dbi']);
+
         $this->designerCommon->getTablePositions($pg);
     }
 
@@ -112,6 +113,8 @@ class CommonTest extends TestCase
             ->will($this->returnValue(array($pageName)));
         $GLOBALS['dbi'] = $dbi;
 
+        $this->designerCommon = new Common($GLOBALS['dbi']);
+
         $result = $this->designerCommon->getPageName($pg);
 
         $this->assertEquals($pageName, $result);
@@ -140,6 +143,7 @@ class CommonTest extends TestCase
             ->will($this->returnArgument(0));
 
         $GLOBALS['dbi'] = $dbi;
+        $this->designerCommon = new Common($GLOBALS['dbi']);
 
         $result = $this->designerCommon->deletePage($pg);
         $this->assertEquals(true, $result);
@@ -176,6 +180,7 @@ class CommonTest extends TestCase
             ->will($this->returnArgument(0));
 
         $GLOBALS['dbi'] = $dbi;
+        $this->designerCommon = new Common($GLOBALS['dbi']);
 
         $result = $this->designerCommon->getDefaultPage($db);
         $this->assertEquals($default_pg, $result);
@@ -210,6 +215,7 @@ class CommonTest extends TestCase
             ->will($this->returnArgument(0));
 
         $GLOBALS['dbi'] = $dbi;
+        $this->designerCommon = new Common($GLOBALS['dbi']);
 
         $result = $this->designerCommon->getDefaultPage($db);
         $this->assertEquals(-1, $result);
@@ -245,6 +251,7 @@ class CommonTest extends TestCase
             ->will($this->returnArgument(0));
 
         $GLOBALS['dbi'] = $dbi;
+        $this->designerCommon = new Common($GLOBALS['dbi']);
 
         $result = $this->designerCommon->getLoadingPage($db);
         $this->assertEquals($default_pg, $result);
@@ -274,6 +281,7 @@ class CommonTest extends TestCase
             ->will($this->returnArgument(0));
 
         $GLOBALS['dbi'] = $dbi;
+        $this->designerCommon = new Common($GLOBALS['dbi']);
 
         $result = $this->designerCommon->getLoadingPage($db);
         $this->assertEquals($first_pg, $result);
diff --git a/test/classes/Database/DesignerTest.php b/test/classes/Database/DesignerTest.php
index a2476faf6e..1985eafcff 100644
--- a/test/classes/Database/DesignerTest.php
+++ b/test/classes/Database/DesignerTest.php
@@ -50,8 +50,6 @@ class DesignerTest extends TestCase
             ],
             ' PMA_token ' => 'token'
         ];
-
-        $this->designer = new Designer();
     }
 
     /**
@@ -103,6 +101,8 @@ class DesignerTest extends TestCase
         $db = 'db';
         $this->_mockDatabaseInteraction($db);
 
+        $this->designer = new Designer($GLOBALS['dbi']);
+
         $method = new ReflectionMethod(Designer::class, 'getPageIdsAndNames');
         $method->setAccessible(true);
         $result = $method->invokeArgs($this->designer, [$db]);
@@ -127,6 +127,8 @@ class DesignerTest extends TestCase
         $operation = 'edit';
         $this->_mockDatabaseInteraction($db);
 
+        $this->designer = new Designer($GLOBALS['dbi']);
+
         $result = $this->designer->getHtmlForEditOrDeletePages($db, $operation);
         $this->assertContains(
             '<input type="hidden" name="operation" value="' . $operation . '" />',
@@ -153,6 +155,8 @@ class DesignerTest extends TestCase
         $db = 'db';
         $this->_mockDatabaseInteraction($db);
 
+        $this->designer = new Designer($GLOBALS['dbi']);
+
         $result = $this->designer->getHtmlForPageSaveAs($db);
         $this->assertContains(
             '<input type="hidden" name="operation" value="savePage" />',
@@ -193,6 +197,8 @@ class DesignerTest extends TestCase
         $db = 'db';
         $page = 2;
 
+        $this->designer = new Designer($GLOBALS['dbi']);
+
         $result = $this->designer->getHtmlForSchemaExport($db, $page);
         // export type
         $this->assertContains(
diff --git a/test/classes/Database/QbeTest.php b/test/classes/Database/QbeTest.php
index b99dbcd5b5..12aad29d5c 100644
--- a/test/classes/Database/QbeTest.php
+++ b/test/classes/Database/QbeTest.php
@@ -9,6 +9,7 @@ declare(strict_types=1);
 namespace PhpMyAdmin\Tests\Database;
 
 use PhpMyAdmin\Database\Qbe;
+use PhpMyAdmin\DatabaseInterface;
 use PhpMyAdmin\Tests\PmaTestCase;
 use ReflectionClass;
 
@@ -33,11 +34,11 @@ class QbeTest extends PmaTestCase
      */
     protected function setUp()
     {
-        $this->object = new Qbe('pma_test');
+        $this->object = new Qbe($GLOBALS['dbi'], 'pma_test');
         $GLOBALS['server'] = 0;
         $GLOBALS['db'] = 'pma_test';
         //mock DBI
-        $dbi = $this->getMockBuilder('PhpMyAdmin\DatabaseInterface')
+        $dbi = $this->getMockBuilder(DatabaseInterface::class)
             ->disableOriginalConstructor()
             ->getMock();
 
@@ -58,6 +59,7 @@ class QbeTest extends PmaTestCase
             ->will($this->returnValue(array()));
 
         $GLOBALS['dbi'] = $dbi;
+        $this->object->dbi = $dbi;
     }
 
     /**
diff --git a/test/classes/Database/SearchTest.php b/test/classes/Database/SearchTest.php
index 1b67fd73ba..0b11e15e0b 100644
--- a/test/classes/Database/SearchTest.php
+++ b/test/classes/Database/SearchTest.php
@@ -34,7 +34,6 @@ class SearchTest extends PmaTestCase
      */
     protected function setUp()
     {
-        $this->object = new Search('pma_test');
         $GLOBALS['server'] = 0;
         $GLOBALS['db'] = 'pma';
 
@@ -56,6 +55,7 @@ class SearchTest extends PmaTestCase
             ->will($this->returnArgument(0));
 
         $GLOBALS['dbi'] = $dbi;
+        $this->object = new Search($dbi, 'pma_test');
     }
 
     /**
@@ -101,7 +101,7 @@ class SearchTest extends PmaTestCase
         $_REQUEST['criteriaSearchType'] = $type;
         $_REQUEST['criteriaSearchString'] = 'search string';
 
-        $this->object = new Search('pma_test');
+        $this->object = new Search($GLOBALS['dbi'], 'pma_test');
         $this->assertEquals(
             $expected,
             $this->callProtectedFunction(