diff --git a/.github/workflows/ezsql-linux.yml b/.github/workflows/ezsql-linux.yml
index edcf3759..c444c550 100644
--- a/.github/workflows/ezsql-linux.yml
+++ b/.github/workflows/ezsql-linux.yml
@@ -12,12 +12,12 @@ on:
 jobs:
   linux:
     name: Linux (PHP ${{ matrix.php-versions }} CI)
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-18.04
     strategy:
       fail-fast: false
       matrix:
-        operating-system: [ubuntu-latest]
-        php-versions: ['7.4', '8.0']
+        operating-system: [ubuntu-18.04]
+        php-versions: ['7.4', '8.0', '8.1']
 
     steps:
       - name: Checkout
diff --git a/.github/workflows/ezsql-macos.yml b/.github/workflows/ezsql-macos.yml
index 155c46bf..6073157c 100644
--- a/.github/workflows/ezsql-macos.yml
+++ b/.github/workflows/ezsql-macos.yml
@@ -34,9 +34,10 @@ jobs:
           brew install mysql@5.7
       - name: Brew Start MySQL
         run: |
-          brew services start mysql@5.7
           brew link mysql@5.7 --force
-          mysqld --initialize-insecure
+          sudo rm -rf /usr/local/var/mysql
+          sudo rm /usr/local/etc/my.cnf
+          mysqld --initialize-insecure --explicit_defaults_for_timestamp
           mysql.server start
       - name: Setup MySQL Database
         run: |
diff --git a/README.md b/README.md
index d8c8aaf1..8afcb5ec 100644
--- a/README.md
+++ b/README.md
@@ -67,7 +67,7 @@ $db = Database::initialize('****', [$dsn_path_user, $password, $database, $other
 use ezsql\Config;
 use ezsql\Database\ez_****;
 
-$setting = new Config('****', [$dsn_path_user, $password, $database, $other_settings]);
+$settings = new Config('****', [$dsn_path_user, $password, $database, $other_settings]);
 
 $db = new ez_****($settings);
 ```
diff --git a/composer.json b/composer.json
index d28eda0a..49262b9c 100644
--- a/composer.json
+++ b/composer.json
@@ -39,7 +39,7 @@
         "issues": "https://github.com/ezSQL/ezSQL/issues"
     },
     "require": {
-        "php": "^7.1 || ^8",
+        "php": ">7.1",
         "psr/container": "^1.0"
     },
     "provide": {
@@ -55,7 +55,7 @@
         }
     },
     "require-dev": {
-        "phpunit/phpunit": "^6 || ^7 || ^8"
+        "phpunit/phpunit": "^6 | ^7 | ^8"
     },
     "autoload-dev": {
         "psr-4": {
diff --git a/lib/Constants.php b/lib/Constants.php
index 789a63e7..c24c1f3c 100644
--- a/lib/Constants.php
+++ b/lib/Constants.php
@@ -5,7 +5,7 @@
     /**
      * ezsqlModel Constants
      */
-    \defined('EZSQL_VERSION') or \define('EZSQL_VERSION', '5.1.1');
+    \defined('EZSQL_VERSION') or \define('EZSQL_VERSION', '5.1.2');
     \defined('OBJECT') or \define('OBJECT', 'OBJECT');
     \defined('ARRAY_A') or \define('ARRAY_A', 'ARRAY_A');
     \defined('ARRAY_N') or \define('ARRAY_N', 'ARRAY_N');
@@ -39,8 +39,8 @@
     \define('_BETWEEN', 'BETWEEN');
     \define('_notBETWEEN', 'NOT BETWEEN');
 
-    \define('_isNULL', 'IS NULL');
-    \define('_notNULL', 'IS NOT NULL');
+    \define('_isNULL', 'IS');
+    \define('_notNULL', 'IS NOT');
     \define('_BOOLEAN_OPERATORS', [
         '<', '>', '=', '!=', '>=', '<=', '<>',
         'IN', 'LIKE', 'NOT LIKE', 'BETWEEN', 'NOT BETWEEN', 'IS', 'IS NOT'
diff --git a/lib/Database.php b/lib/Database.php
index 0b028739..4baf5e72 100644
--- a/lib/Database.php
+++ b/lib/Database.php
@@ -4,8 +4,8 @@
 
 namespace ezsql;
 
+use ezsql\Db;
 use ezsql\DInjector;
-use function ezsql\functions\setInstance;
 
 class Database
 {
@@ -15,9 +15,13 @@ class Database
      * @var float
      */
     private static $_ts = null;
-    private static $factory = null;
+
+    /**
+     * @var ezQueryInterface[]
+     */
     private static $instances = [];
 
+    // @codeCoverageIgnoreStart
     private function __construct()
     {
     }
@@ -27,6 +31,7 @@ private function __clone()
     public function __wakeup()
     {
     }
+    // @codeCoverageIgnoreEnd
 
     /**
      * Initialize and connect a vendor database.
@@ -65,10 +70,10 @@ public function __wakeup()
      * @param string $tag Store the instance for later use
      * @return Database\ez_pdo|Database\ez_pgsql|Database\ez_sqlsrv|Database\ez_sqlite3|Database\ez_mysqli
      */
-    public static function initialize(?string $vendor = null, ?array $setting = null, ?string $tag = null)
+    public static function initialize(?string $vendor = null, ?array $setting = null, ?string $tag = null): ezQueryInterface
     {
         if (isset(self::$instances[$vendor]) && empty($setting) && empty($tag))
-            return setInstance(self::$instances[$vendor]) ? self::$instances[$vendor] : false;
+            return self::$instances[$vendor];
 
         if (empty($vendor) || empty($setting)) {
             throw new \Exception(\MISSING_CONFIGURATION);
@@ -77,7 +82,7 @@ public static function initialize(?string $vendor = null, ?array $setting = null
             $key = $vendor;
             $value = \VENDOR[$key];
 
-            if (empty($GLOBALS['ez' . $key]) || !empty($tag)) {
+            if (!Db::has('ez' . $key) || !empty($tag)) {
                 $di = new DInjector();
                 $di->set($key, $value);
                 $di->set('ezsql\ConfigInterface', 'ezsql\Config');
@@ -88,8 +93,9 @@ public static function initialize(?string $vendor = null, ?array $setting = null
                 }
             }
 
-            setInstance($GLOBALS['ez' . $key]);
-            return $GLOBALS['ez' . $key];
+            $db = Db::get('ez' . $key);
+            Db::set('global', $db);
+            return $db;
         }
     }
 
diff --git a/lib/Database/ez_mysqli.php b/lib/Database/ez_mysqli.php
index 7de25a4f..0d338359 100644
--- a/lib/Database/ez_mysqli.php
+++ b/lib/Database/ez_mysqli.php
@@ -5,10 +5,10 @@
 namespace ezsql\Database;
 
 use Exception;
+use ezsql\Db;
 use ezsql\ezsqlModel;
 use ezsql\ConfigInterface;
 use ezsql\DatabaseInterface;
-use function ezsql\functions\setInstance;
 
 class ez_mysqli extends ezsqlModel implements DatabaseInterface
 {
@@ -44,9 +44,9 @@ public function __construct(ConfigInterface $settings = null)
         parent::__construct();
         $this->database = $settings;
 
-        if (empty($GLOBALS['ez' . \MYSQLI]))
-            $GLOBALS['ez' . \MYSQLI] = $this;
-        setInstance($this);
+        if (!Db::has('ez' . \MYSQLI))
+            Db::set('ez' . \MYSQLI, $this);
+        Db::set('global', $this);
     } // __construct
 
     public function settings()
@@ -291,7 +291,7 @@ public function query_prepared(string $query, array $param = null)
         $params = [];
         $types = \array_reduce(
             $param,
-            function ($string, &$arg) use (&$params) {
+            function ($string, $arg) use (&$params) {
                 $params[] = &$arg;
                 if (\is_float($arg))
                     $string .= 'd';
diff --git a/lib/Database/ez_pdo.php b/lib/Database/ez_pdo.php
index eec3acd1..644afbed 100644
--- a/lib/Database/ez_pdo.php
+++ b/lib/Database/ez_pdo.php
@@ -5,10 +5,10 @@
 namespace ezsql\Database;
 
 use Exception;
+use ezsql\Db;
 use ezsql\ezsqlModel;
 use ezsql\ConfigInterface;
 use ezsql\DatabaseInterface;
-use function ezsql\functions\setInstance;
 
 class ez_pdo extends ezsqlModel implements DatabaseInterface
 {
@@ -47,9 +47,9 @@ public function __construct(ConfigInterface $settings = null)
         // Turn on track errors
         ini_set('track_errors', '1');
 
-        if (empty($GLOBALS['ez' . \Pdo]))
-            $GLOBALS['ez' . \Pdo] = $this;
-        setInstance($this);
+        if (!Db::has('ez' . \Pdo))
+            Db::set('ez' . \Pdo, $this);
+        Db::set('global', $this);
     } // __construct
 
     public function settings()
diff --git a/lib/Database/ez_pgsql.php b/lib/Database/ez_pgsql.php
index 71f5aeb7..8ace292a 100644
--- a/lib/Database/ez_pgsql.php
+++ b/lib/Database/ez_pgsql.php
@@ -5,10 +5,10 @@
 namespace ezsql\Database;
 
 use Exception;
+use ezsql\Db;
 use ezsql\ezsqlModel;
 use ezsql\ConfigInterface;
 use ezsql\DatabaseInterface;
-use function ezsql\functions\setInstance;
 
 class ez_pgsql extends ezsqlModel implements DatabaseInterface
 {
@@ -44,9 +44,9 @@ public function __construct(ConfigInterface $settings = null)
         parent::__construct();
         $this->database = $settings;
 
-        if (empty($GLOBALS['ez' . \PGSQL]))
-            $GLOBALS['ez' . \PGSQL] = $this;
-        setInstance($this);
+        if (!Db::has('ez' . \PGSQL))
+            Db::set('ez' . \PGSQL, $this);
+        Db::set('global', $this);
     } // __construct
 
     public function settings()
diff --git a/lib/Database/ez_sqlite3.php b/lib/Database/ez_sqlite3.php
index f36ac7f6..1cf729f7 100644
--- a/lib/Database/ez_sqlite3.php
+++ b/lib/Database/ez_sqlite3.php
@@ -5,10 +5,10 @@
 namespace ezsql\Database;
 
 use Exception;
+use ezsql\Db;
 use ezsql\ezsqlModel;
 use ezsql\ConfigInterface;
 use ezsql\DatabaseInterface;
-use function ezsql\functions\setInstance;
 
 class ez_sqlite3 extends ezsqlModel implements DatabaseInterface
 {
@@ -51,9 +51,9 @@ public function __construct(ConfigInterface $settings = null)
         // Turn on track errors
         ini_set('track_errors', '1');
 
-        if (!isset($GLOBALS['ez' . \SQLITE3]))
-            $GLOBALS['ez' . \SQLITE3] = $this;
-        setInstance($this);
+        if (!Db::has('ez' . \SQLITE3))
+            Db::set('ez' . \SQLITE3, $this);
+        Db::set('global', $this);
     }
 
     public function settings()
diff --git a/lib/Database/ez_sqlsrv.php b/lib/Database/ez_sqlsrv.php
index aca7a533..fb0f34e0 100644
--- a/lib/Database/ez_sqlsrv.php
+++ b/lib/Database/ez_sqlsrv.php
@@ -5,10 +5,10 @@
 namespace ezsql\Database;
 
 use Exception;
+use ezsql\Db;
 use ezsql\ezsqlModel;
 use ezsql\ConfigInterface;
 use ezsql\DatabaseInterface;
-use function ezsql\functions\setInstance;
 
 class ez_sqlsrv extends ezsqlModel implements DatabaseInterface
 {
@@ -53,9 +53,9 @@ public function __construct(ConfigInterface $settings = null)
         parent::__construct();
         $this->database = $settings;
 
-        if (empty($GLOBALS['ez' . \SQLSRV]))
-            $GLOBALS['ez' . \SQLSRV] = $this;
-        setInstance($this);
+        if (!Db::has('ez' . \SQLSRV))
+            Db::set('ez' . \SQLSRV, $this);
+        Db::set('global', $this);
     }
 
     public function settings()
diff --git a/lib/Db.php b/lib/Db.php
new file mode 100644
index 00000000..2da863e3
--- /dev/null
+++ b/lib/Db.php
@@ -0,0 +1,66 @@
+<?php
+
+declare(strict_types=1);
+
+namespace ezsql;
+
+use ezsql\ezQueryInterface;
+
+/**
+ * Used internally for needed **global** variables.
+ *
+ * @internal
+ */
+final class Db
+{
+    /**
+     * @var ezQueryInterface[]
+     */
+    protected static $storage;
+
+    /**
+     * @param string $key
+     * @param mixed $value
+     * @return void
+     */
+    public static function set(string $key, $value): void
+    {
+        self::$storage[$key] = $value;
+    }
+
+    /**
+     * @param string $key
+     * @return ezQueryInterface
+     */
+    public static function get(string $key): ?ezQueryInterface
+    {
+        return self::$storage[$key] ?? null;
+    }
+
+    /**
+     * @param string $tag
+     * @return boolean
+     */
+    public static function has(string $tag): bool
+    {
+        return isset(self::$storage[$tag]);
+    }
+
+    /**
+     * @param string $tag
+     * @return void
+     */
+    public static function clear(string $tag): void
+    {
+        if (self::has($tag))
+            unset(self::$storage[$tag]);
+    }
+
+    /**
+     * @return void
+     */
+    public static function reset(): void
+    {
+        self::$storage = null;
+    }
+}
diff --git a/lib/ezFunctions.php b/lib/ezFunctions.php
index 4a10aafb..615b7aed 100644
--- a/lib/ezFunctions.php
+++ b/lib/ezFunctions.php
@@ -4,6 +4,7 @@
 
 namespace ezsql\functions;
 
+use ezsql\Db;
 use ezsql\ezQuery;
 use ezsql\ezSchema;
 use ezsql\Database;
@@ -12,6 +13,24 @@
 use ezsql\ezsqlModelInterface;
 
 if (!\function_exists('ezFunctions')) {
+    /**
+     * Returns the global database class, last created instance.
+     *
+     * @return ezQueryInterface|null
+     */
+    function getInstance(): ?ezQueryInterface
+    {
+        return Db::get('global');
+    }
+
+    /**
+     * Clear/unset the global database class instance.
+     */
+    function clearInstance(): void
+    {
+        Db::clear('global');
+    }
+
     /**
      * Initialize and connect a vendor's database.
      *
@@ -138,7 +157,7 @@ function sqliteInstance(array $databaseSetting = null, string $instanceTag = nul
      *
      * @return string|null `mysqli`|`pgsql`|`sqlite3`|`sqlsrv`
      */
-    function get_vendor(DatabaseInterface $instance = null)
+    function get_vendor(DatabaseInterface $instance = null): ?string
     {
         return ezSchema::vendor($instance);
     }
@@ -148,7 +167,7 @@ function get_vendor(DatabaseInterface $instance = null)
      *
      * @return string
      */
-    function to_string($arrays, $separation = ',')
+    function to_string($arrays, $separation = ','): string
     {
         return ezQuery::to_string($arrays, $separation);
     }
@@ -225,7 +244,7 @@ function changingColumn(string $columnName, ...$datatype)
      *
      * @return array
      */
-    function eq($x, $y, $and = null, ...$args)
+    function eq($x, $y, $and = null, ...$args): array
     {
         $expression = array();
         \array_push($expression, $x, \EQ, $y, $and, ...$args);
@@ -251,7 +270,7 @@ function eq($x, $y, $and = null, ...$args)
      *
      * @return array
      */
-    function neq($x, $y, $and = null, ...$args)
+    function neq($x, $y, $and = null, ...$args): array
     {
         $expression = array();
         \array_push($expression, $x, \NEQ, $y, $and, ...$args);
@@ -268,7 +287,7 @@ function neq($x, $y, $and = null, ...$args)
      *
      * @return array
      */
-    function ne($x, $y, $and = null, ...$args)
+    function ne($x, $y, $and = null, ...$args): array
     {
         $expression = array();
         \array_push($expression, $x, \NE, $y, $and, ...$args);
@@ -285,7 +304,7 @@ function ne($x, $y, $and = null, ...$args)
      *
      * @return array
      */
-    function lt($x, $y, $and = null, ...$args)
+    function lt($x, $y, $and = null, ...$args): array
     {
         $expression = array();
         \array_push($expression, $x, \LT, $y, $and, ...$args);
@@ -302,7 +321,7 @@ function lt($x, $y, $and = null, ...$args)
      *
      * @return array
      */
-    function lte($x, $y, $and = null, ...$args)
+    function lte($x, $y, $and = null, ...$args): array
     {
         $expression = array();
         \array_push($expression, $x, \LTE, $y, $and, ...$args);
@@ -319,7 +338,7 @@ function lte($x, $y, $and = null, ...$args)
      *
      * @return array
      */
-    function gt($x, $y, $and = null, ...$args)
+    function gt($x, $y, $and = null, ...$args): array
     {
         $expression = array();
         \array_push($expression, $x, \GT, $y, $and, ...$args);
@@ -336,7 +355,7 @@ function gt($x, $y, $and = null, ...$args)
      *
      * @return array
      */
-    function gte($x, $y, $and = null, ...$args)
+    function gte($x, $y, $and = null, ...$args): array
     {
         $expression = array();
         \array_push($expression, $x, \GTE, $y, $and, ...$args);
@@ -353,7 +372,7 @@ function gte($x, $y, $and = null, ...$args)
      *
      * @return array
      */
-    function isNull($x, $y = 'null', $and = null, ...$args)
+    function isNull($x, $y = 'null', $and = null, ...$args): array
     {
         $expression = array();
         \array_push($expression, $x, \_isNULL, $y, $and, ...$args);
@@ -370,7 +389,7 @@ function isNull($x, $y = 'null', $and = null, ...$args)
      *
      * @return array
      */
-    function isNotNull($x, $y = 'null', $and = null, ...$args)
+    function isNotNull($x, $y = 'null', $and = null, ...$args): array
     {
         $expression = array();
         \array_push($expression, $x, \_notNULL, $y, $and, ...$args);
@@ -387,7 +406,7 @@ function isNotNull($x, $y = 'null', $and = null, ...$args)
      *
      * @return array
      */
-    function like($x, $y, $and = null, ...$args)
+    function like($x, $y, $and = null, ...$args): array
     {
         $expression = array();
         \array_push($expression, $x, \_LIKE, $y, $and, ...$args);
@@ -404,7 +423,7 @@ function like($x, $y, $and = null, ...$args)
      *
      * @return array
      */
-    function notLike($x, $y, $and = null, ...$args)
+    function notLike($x, $y, $and = null, ...$args): array
     {
         $expression = array();
         \array_push($expression, $x, \_notLIKE, $y, $and, ...$args);
@@ -421,7 +440,7 @@ function notLike($x, $y, $and = null, ...$args)
      *
      * @return array
      */
-    function in($x, $y, ...$args)
+    function in($x, $y, ...$args): array
     {
         $expression = array();
         \array_push($expression, $x, \_IN, $y, ...$args);
@@ -438,7 +457,7 @@ function in($x, $y, ...$args)
      *
      * @return array
      */
-    function notIn($x, $y, ...$args)
+    function notIn($x, $y, ...$args): array
     {
         $expression = array();
         \array_push($expression, $x, \_notIN, $y, ...$args);
@@ -455,7 +474,7 @@ function notIn($x, $y, ...$args)
      *
      * @return array
      */
-    function between($x, $y, $y2, ...$args)
+    function between($x, $y, $y2, ...$args): array
     {
         $expression = array();
         \array_push($expression, $x, \_BETWEEN, $y, $y2, \_AND, ...$args);
@@ -472,45 +491,13 @@ function between($x, $y, $y2, ...$args)
      *
      * @return array
      */
-    function notBetween($x, $y, $y2, ...$args)
+    function notBetween($x, $y, $y2, ...$args): array
     {
         $expression = array();
         \array_push($expression, $x, \_notBETWEEN, $y, $y2, \_AND, ...$args);
         return $expression;
     }
 
-    /**
-     * Sets the global class instance for functions to call class methods directly.
-     *
-     * @param ezQueryInterface|null $ezSQL
-     *
-     * @return boolean - `true`, or `false` for error
-     */
-    function setInstance(ezQueryInterface $ezSQL = null)
-    {
-        global $ezInstance;
-        $status = false;
-
-        if ($ezSQL instanceof ezQueryInterface) {
-            $ezInstance = $ezSQL;
-            $status = true;
-        }
-
-        return $status;
-    }
-
-    /**
-     * Returns the global database class, last created instance or the one set with `setInstance()`.
-     *
-     * @return ezQueryInterface|null
-     */
-    function getInstance()
-    {
-        global $ezInstance;
-
-        return ($ezInstance instanceof ezQueryInterface) ? $ezInstance : null;
-    }
-
     /**
      * Get multiple row result set from the database (previously cached results).
      * Returns a multi dimensional array.
@@ -547,24 +534,13 @@ function get_results($output = \OBJECT, $instance = null)
             : false;
     }
 
-    /**
-     * Clear/unset the global database class instance.
-     */
-    function clearInstance()
-    {
-        global $ezInstance;
-        $GLOBALS['ezInstance'] = null;
-        $ezInstance = null;
-        unset($GLOBALS['ezInstance']);
-    }
-
     /**
      * Clean input string of XSS, html, javascript, etc...
      * @param string $string
      *
      * @return string cleaned string
      */
-    function clean_string(string $string)
+    function clean_string(string $string): string
     {
         $patterns = array( // strip out:
             '@<script[^>]*?>.*?</script>@si', // Strip out javascript
@@ -587,7 +563,7 @@ function clean_string(string $string)
      * @param string $filename will be preprocess with `sanitize_path()`
      * @return boolean
      */
-    function is_traversal(string $basePath, string $filename)
+    function is_traversal(string $basePath, string $filename): bool
     {
         if (\strpos(\urldecode($filename), '..') !== false)
             return true;
@@ -607,17 +583,17 @@ function is_traversal(string $basePath, string $filename)
      *
      * Example:
      *
-     *  `sanitize_path("../../../../config.php");`
-     *
-     *      Returns `config.php` without the path traversal
-     * @param string $path
+     * `sanitize_path("../../../../config.php-");`
+     * - Returns `config.php` without the path traversal
+     * @param string $path original file/path to be sanitized.
      * @return string
      */
-    function sanitize_path(string $path)
+    function sanitize_path(string $path): string
     {
         $file = \preg_replace("/\.[\.]+/", "", $path);
         $file = \preg_replace("/^[\/]+/", "", $file);
         $file = \preg_replace("/^[A-Za-z][:\|][\/]?/", "", $file);
+        $file = \trim($file, '.-_');
         return ($file);
     }
 
@@ -965,14 +941,32 @@ function set_prefix(string $append = '')
 
     /**
      * Does an `select into` statement by calling `select` method
-     * @param $newTable, - new database table to be created
-     * @param $fromColumns - the columns from old database table
-     * @param $oldTable - old database table
-     * @param $fromWhereConditions, - where clause `eq(x, y, _AND), another clause - same as array(x, =, y, and, extra) `
-     *
-     * @return mixed|object bool/result - false for error
+     * @param string $newTable, - new database table to be created
+     * @param mixed $fromColumns - the columns from old database table
+     * @param string $oldTable - old database table
+     * @param mixed $fromWhereConditions, - where clause `eq(x, y, _AND), another clause - same as array(x, =, y, and, extra)`
+     * - In the following format:
+     *```js
+     *   eq('key/Field/Column', $value, _AND), // combine next expression
+     *   neq('key/Field/Column', $value, _OR), // will combine next expression if
+     *   ne('key/Field/Column', $value), // the default is _AND so will combine next expression
+     *   lt('key/Field/Column', $value)
+     *   lte('key/Field/Column', $value)
+     *   gt('key/Field/Column', $value)
+     *   gte('key/Field/Column', $value)
+     *   isNull('key/Field/Column')
+     *   isNotNull('key/Field/Column')
+     *   like('key/Field/Column', '_%')
+     *   notLike('key/Field/Column', '_%')
+     *   in('key/Field/Column', $values)
+     *   notIn('key/Field/Column', $values)
+     *   between('key/Field/Column', $value, $value2)
+     *   notBetween('key/Field/Column', $value, $value2)
+     *```
+     * @return mixed bool/result - false for error
+     * @codeCoverageIgnore
      */
-    function select_into($newTable, $fromColumns = '*', $oldTable = null, ...$fromWhereConditions)
+    function select_into(string $newTable, $fromColumns = '*', string $oldTable = null, ...$fromWhereConditions)
     {
         $ezQuery = getInstance();
         return ($ezQuery instanceof DatabaseInterface)
@@ -1096,15 +1090,15 @@ function grouping(...$conditions)
      *        having( between( 'columns', values1, values2 ) ),
      *        orderBy( 'columns', 'desc' );
      *</code>
-     * @param mixed $groupBy The grouping expression.
+     * @param string|array $column The grouping expression.
      *
      * @return string - GROUP BY SQL statement, or false on error
      */
-    function groupBy($groupBy)
+    function groupBy($column)
     {
         $ezQuery = getInstance();
         return ($ezQuery instanceof DatabaseInterface)
-            ? $ezQuery->groupBy($groupBy)
+            ? $ezQuery->groupBy($column)
             : false;
     }
 
@@ -1364,16 +1358,16 @@ function unionAll($table = '', $columnFields = '*', ...$conditions)
 
     /**
      * Specifies an ordering for the query results.
-     * @param string $orderBy - The column.
-     * @param string $order - The ordering direction.
+     * @param string|array $column - Which columns to use for ordering.
+     * @param string $order - The ordering direction, either `ASC`|`DESC`.
      *
      * @return string - ORDER BY SQL statement, or false on error
      */
-    function orderBy($orderBy, $order)
+    function orderBy($column, $order)
     {
         $ezQuery = getInstance();
         return ($ezQuery instanceof DatabaseInterface)
-            ? $ezQuery->orderBy($orderBy, $order)
+            ? $ezQuery->orderBy($column, $order)
             : false;
     }
 
@@ -1394,6 +1388,9 @@ function limit($numberOf, $offset = null)
             : false;
     }
 
+    /**
+     * @codeCoverageIgnore
+     */
     function ezFunctions()
     {
         return true;
diff --git a/lib/ezQuery.php b/lib/ezQuery.php
index cbc413cf..4d0ff831 100644
--- a/lib/ezQuery.php
+++ b/lib/ezQuery.php
@@ -111,13 +111,13 @@ public static function to_string($arrays, $separation = ',')
         return $columns;
     }
 
-    public function groupBy($groupBy)
+    public function groupBy($column)
     {
-        if (empty($groupBy)) {
+        if (empty($column)) {
             return false;
         }
 
-        $columns = $this->to_string($groupBy);
+        $columns = $this->to_string($column);
 
         return 'GROUP BY ' . $columns;
     }
@@ -262,15 +262,15 @@ private function joining(
         return ' ' . $type . ' JOIN ' . $rightTable . ' AS ' . $tableAs . ' ' . $onCondition;
     }
 
-    public function orderBy($orderBy, $order)
+    public function orderBy($column, $order)
     {
-        if (empty($orderBy)) {
+        if (empty($column)) {
             return false;
         }
 
-        $columns = $this->to_string($orderBy);
-
-        $order = (\in_array(\strtoupper($order), array('ASC', 'DESC'))) ? \strtoupper($order) : 'ASC';
+        $columns = $this->to_string($column);
+        $by = \strtoupper($order);
+        $order = (\in_array($by, array('ASC', 'DESC'))) ? $by : 'ASC';
 
         return 'ORDER BY ' . $columns . ' ' . $order;
     }
@@ -593,7 +593,10 @@ public function create_select(string $newTable, $fromColumns = '*', $oldTable =
         return $this->clearPrepare();
     }
 
-    public function select_into(string $newTable, $fromColumns = '*', $oldTable = null, ...$fromWhereConditions)
+    /**
+     * @codeCoverageIgnore
+     */
+    public function select_into(string $newTable, $fromColumns = '*', string $oldTable = null, ...$fromWhereConditions)
     {
         $this->isInto = true;
         if (isset($oldTable))
@@ -602,7 +605,7 @@ public function select_into(string $newTable, $fromColumns = '*', $oldTable = nu
             return $this->clearPrepare();
 
         $newTableFromTable = $this->select_sql($newTable, $fromColumns, ...$fromWhereConditions);
-        if (is_string($newTableFromTable))
+        if (\is_string($newTableFromTable))
             return (($this->isPrepareOn()) && !empty($this->prepareValues()))
                 ? $this->query($newTableFromTable, true)
                 : $this->query($newTableFromTable);
@@ -619,7 +622,7 @@ public function update(string $table = null, $keyValue, ...$whereConditions)
         $sql = "UPDATE $table SET ";
 
         foreach ($keyValue as $key => $val) {
-            if (\strtolower($val) == 'null') {
+            if (is_null($val) || \strtolower($val) == 'null') {
                 $sql .= "$key = NULL, ";
             } elseif (\in_array(\strtolower($val), array('current_timestamp()', 'date()', 'now()'))) {
                 $sql .= "$key = CURRENT_TIMESTAMP(), ";
diff --git a/lib/ezQueryInterface.php b/lib/ezQueryInterface.php
index 2fc422ac..14c3f1f7 100644
--- a/lib/ezQueryInterface.php
+++ b/lib/ezQueryInterface.php
@@ -50,11 +50,11 @@ public function prepareOff();
      *        having( between( 'columns', values1, values2 ) ),
      *        orderBy( 'columns', 'desc' );
      *</code>
-     * @param mixed $groupBy The grouping expression.
+     * @param string|array $column The grouping expression.
      *
      * @return string - GROUP BY SQL statement, or false on error
      */
-    public function groupBy($groupBy);
+    public function groupBy($column);
 
     /**
      * Specifies a `restriction` over the groups of the query.
@@ -275,12 +275,12 @@ public function unionAll(string $table = null, $columnFields = '*', ...$conditio
 
     /**
      * Specifies an ordering for the query results.
-     * @param string $orderBy - The column.
-     * @param string $order - The ordering direction.
+     * @param string|array $column - Which columns to use for ordering.
+     * @param string $order - The ordering direction, either `ASC`|`DESC`.
      *
      * @return string - ORDER BY SQL statement, or false on error
      */
-    public function orderBy($orderBy, $order);
+    public function orderBy($column, $order);
 
     /**
      * Specifies records from one or more tables in a database and
@@ -452,10 +452,10 @@ function inserting(array $keyValue);
     /**
      * Does an `create select` statement by calling `select` method
      *
-     * @param $newTable, - new database table to be created
-     * @param $fromColumns - the columns from old database table
-     * @param $oldTable - old database table
-     * @param $fromWhereConditions, - where clause `eq(x, y, _AND), another clause - same as array(x, =, y, and, extra)`
+     * @param string $newTable, - new database table to be created
+     * @param string|array $fromColumns - the columns from old database table
+     * @param string $oldTable - old database table
+     * @param array $fromWhereConditions, - where clause `eq(x, y, _AND), another clause - same as array(x, =, y, and, extra)`
      * - In the following format:
      *```js
      *   eq('key/Field/Column', $value, _AND), // combine next expression
@@ -480,10 +480,10 @@ public function create_select(string $newTable, $fromColumns = '*', $oldTable =
 
     /**
      * Does an `select into` statement by calling `select` method
-     * @param $newTable, - new database table to be created
-     * @param $fromColumns - the columns from old database table
-     * @param $oldTable - old database table
-     * @param $fromWhereConditions, - where clause `eq(x, y, _AND), another clause - same as array(x, =, y, and, extra)`
+     * @param string $newTable, - new database table to be created
+     * @param mixed $fromColumns - the columns from old database table
+     * @param string $oldTable - old database table
+     * @param mixed $fromWhereConditions, - where clause `eq(x, y, _AND), another clause - same as array(x, =, y, and, extra)`
      * - In the following format:
      *```js
      *   eq('key/Field/Column', $value, _AND), // combine next expression
@@ -504,7 +504,7 @@ public function create_select(string $newTable, $fromColumns = '*', $oldTable =
      *```
      * @return mixed bool/result - false for error
      */
-    public function select_into(string $newTable, $fromColumns = '*', $oldTable = null, ...$fromWhereConditions);
+    public function select_into(string $newTable, $fromColumns = '*', string $oldTable = null, ...$fromWhereConditions);
 
     /**
      * Does an `update` query with an array, by conditional operator array
diff --git a/lib/ezResultset.php b/lib/ezResultset.php
index 5a9cc1ac..1eb31a2e 100644
--- a/lib/ezResultset.php
+++ b/lib/ezResultset.php
@@ -64,7 +64,7 @@ public function __construct($query_result)
     /**
      * Sets the position to zero
      */
-    public function rewind()
+    public function rewind(): void
     {
         $this->_position = 0;
     } // rewind
@@ -111,7 +111,7 @@ public function current($mode = self::RESULT_AS_OBJECT)
      * Returns the current position in the resultset
      * @return int
      */
-    public function key()
+    public function key(): int
     {
         return $this->_position;
     } // key
@@ -119,7 +119,7 @@ public function key()
     /**
      * Sets the position of the resultset up by one
      */
-    public function next()
+    public function next(): void
     {
         ++$this->_position;
     } // next
@@ -128,7 +128,7 @@ public function next()
      * Sets position of the resultset down by one, if the position is below the
      * start, the position is set to the start position
      */
-    public function previous()
+    public function previous(): void
     {
         --$this->_position;
 
@@ -141,7 +141,7 @@ public function previous()
      * Whether the current position contains a row, or not
      * @return boolean
      */
-    public function valid()
+    public function valid(): bool
     {
         return isset($this->_resultset[$this->_position]);
     } // valid
@@ -159,6 +159,7 @@ public function fetch_assoc()
         } else {
             $return_val = false;
         }
+
         return $return_val;
     } // fetch_assoc
 
@@ -175,6 +176,7 @@ public function fetch_row()
         } else {
             $return_val = false;
         }
+
         return $return_val;
     } // fetch_row
 
@@ -191,6 +193,7 @@ public function fetch_object()
         } else {
             $return_val = false;
         }
+
         return $return_val;
     } // fetch_object
 
@@ -206,6 +209,7 @@ public function fetch_json()
         } else {
             $return_val = false;
         }
+
         return $return_val;
     } // fetch_assoc
     //public function
diff --git a/tests/ezFunctionsTest.php b/tests/ezFunctionsTest.php
index a8c374a2..6cd3eb7a 100644
--- a/tests/ezFunctionsTest.php
+++ b/tests/ezFunctionsTest.php
@@ -5,7 +5,6 @@
 use ezsql\Tests\EZTestCase;
 
 use function ezsql\functions\{
-    setInstance,
     getInstance,
     clearInstance,
     get_vendor,
@@ -65,12 +64,15 @@ protected function setUp(): void
 
     public function testClean_string()
     {
-        $this->assertEquals("' help", clean_string("<?php echo 'foo' >' help</php?>"));
+        if ((float) \phpversion() >= 8.1)
+            $this->assertEquals("&#039; help", clean_string("<?php echo 'foo' >' help</php?>"));
+        else
+            $this->assertEquals("' help", clean_string("<?php echo 'foo' >' help</php?>"));
     }
 
     public function testSanitize_path()
     {
-        $this->assertEquals("config.php", sanitize_path("../../../../config.php"));
+        $this->assertEquals("config.php", sanitize_path("../../../../config.php-"));
     }
 
     public function testis_traversal()
@@ -174,13 +176,13 @@ public function testGte()
     public function testIsNull()
     {
         $this->assertIsArray(isNull('field'));
-        $this->assertArraySubset([2 => 'null'], isNull('field'));
+        $this->assertArraySubset([2 => 'NULL'], isNull('field'));
     }
 
     public function testIsNotNull()
     {
         $this->assertIsArray(isNotNull('field'));
-        $this->assertArraySubset([2 => 'null'], isNotNull('field'));
+        $this->assertArraySubset([2 => 'NULL'], isNotNull('field'));
     }
 
     public function testLike()
@@ -219,11 +221,6 @@ public function testNotBetween()
         $this->assertArraySubset([3 => 'data2'], notBetween('field', 'data', 'data2'));
     }
 
-    public function testSetInstance()
-    {
-        $this->assertFalse(setInstance());
-    }
-
     public function testSelect_into()
     {
         $this->assertFalse(select_into('field', 'data', 'data2'));
diff --git a/tests/mysqli/mysqliTest.php b/tests/mysqli/mysqliTest.php
index 534f7ef4..85e7e9ff 100644
--- a/tests/mysqli/mysqliTest.php
+++ b/tests/mysqli/mysqliTest.php
@@ -25,6 +25,9 @@
     dropping,
     altering,
     get_results,
+    groupBy,
+    limit,
+    orderBy,
     replacing,
     table_setup,
     where
@@ -96,7 +99,12 @@ public function testConnect()
         $this->errors = array();
         set_error_handler(array($this, 'errorHandler'));
 
-        $this->assertFalse($this->object->connect('no', ''));
+        if ((float) \phpversion() >= 8.1) {
+            $this->expectException(\mysqli_sql_exception::class);
+            $this->assertFalse($this->object->connect('no', ''));
+        } else
+            $this->assertFalse($this->object->connect('no', ''));
+
         $this->assertFalse($this->object->connect('self::TEST_DB_USER', 'self::TEST_DB_PASSWORD', ' self::TEST_DB_HOST', 'self::TEST_DB_PORT'));
         $result = $this->object->connect(self::TEST_DB_USER, self::TEST_DB_PASSWORD);
 
@@ -281,8 +289,17 @@ public function testCreatingReplacing()
     {
         $this->object->quick_connect();
         $this->object->prepareOff();
-        $this->assertFalse($this->object->replacing([]));
-        $this->assertFalse($this->object->creating([]));
+        if ((float) \phpversion() >= 8.1) {
+            $this->expectException(\mysqli_sql_exception::class);
+            $this->assertFalse($this->object->replacing([]));
+        } else
+            $this->assertFalse($this->object->replacing([]));
+
+        if ((float) \phpversion() >= 8.1) {
+            $this->expectException(\mysqli_sql_exception::class);
+            $this->assertFalse($this->object->creating([]));
+        } else
+            $this->assertFalse($this->object->creating([]));
 
         set_table('unit_test');
         $this->assertEquals(
@@ -603,7 +620,14 @@ public function testSelectAndCreateTable()
             ])
         );
 
-        $result = $this->object->select('users', 'id, tel_num, email', eq('user_name ', 'walker'));
+        $result = $this->object->select(
+            'users',
+            'id, tel_num, email',
+            where(eq('user_name ', 'walker')),
+            groupBy('id'),
+            orderBy('id', 'ASC'),
+            limit(1)
+        );
 
         $this->object->debugOn();
         $this->expectOutputRegex('/[123456]/');