diff --git a/.phpstan.neon b/.phpstan.neon
new file mode 100644
index 00000000..e61e6961
--- /dev/null
+++ b/.phpstan.neon
@@ -0,0 +1,3 @@
+parameters:
+	ignoreErrors:
+		- '#(sqlsrv|SQLSRV).+ not found\.#i'
diff --git a/.travis.yml b/.travis.yml
index 71e77cc9..54d315eb 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -3,6 +3,7 @@ language: php
 php:
     - 7.0
     - 7.1
+    - 7.2
 
 matrix:
     fast_finish: true
@@ -21,8 +22,8 @@ before_script:
     # Create php.ini & databases.ini
     - cp ./tests/php.unix-sample.ini ./tests/php.ini
 
-    - if [ "$TRAVIS_PHP_VERSION" == "7.0" ]; then cat ~/.phpenv/versions/$(phpenv version-name)/etc/conf.d/xdebug.ini >> ./tests/php.ini; fi
-    - if [ "$TRAVIS_PHP_VERSION" == "7.0" ]; then NTESTER_FLAGS="--coverage ./coverage.xml --coverage-src ./src"; else TESTER_FLAGS=""; fi
+    - if [ "$TRAVIS_PHP_VERSION" == "7.2" ]; then cat ~/.phpenv/versions/$(phpenv version-name)/etc/conf.d/xdebug.ini >> ./tests/php.ini; fi
+    - if [ "$TRAVIS_PHP_VERSION" == "7.2" ]; then NTESTER_FLAGS="--coverage ./coverage.xml --coverage-src ./src"; else TESTER_FLAGS=""; fi
     - cp ./tests/databases.sample.ini ./tests/databases.ini
 
     # Create MySQL & Postgre database
@@ -37,12 +38,14 @@ before_script:
     - phpenv config-rm xdebug.ini
     - travis_retry composer update --no-interaction
 
-script: ./tests/run.sh -s $NTESTER_FLAGS ./tests/cases
+script:
+    - ./tests/run.sh -s $NTESTER_FLAGS ./tests/cases
+    - if [ "$TRAVIS_PHP_VERSION" == "7.2" ]; then vendor/bin/phpstan.phar analyse -l 7 -c .phpstan.neon src; fi
 
 after_script:
-    - if [ "$TRAVIS_PHP_VERSION" == "7.0" ]; then
-      wget https://github.com/satooshi/php-coveralls/releases/download/v1.0.1/coveralls.phar
-      && php coveralls.phar --verbose --config tests/.coveralls.yml
+    - if [ "$TRAVIS_PHP_VERSION" == "7.2" ]; then
+      wget https://github.com/satooshi/php-coveralls/releases/download/v2.0.0/php-coveralls.phar
+      && php php-coveralls.phar --verbose --config tests/.coveralls.yml
       || true;
       fi
 
diff --git a/composer.json b/composer.json
index 7b521244..cd913e43 100644
--- a/composer.json
+++ b/composer.json
@@ -15,11 +15,12 @@
 		"php": ">=7.0"
 	},
 	"require-dev": {
-		"nette/tester": "~1.7",
-		"nette/caching": "~2.2",
 		"mockery/mockery": "~1.0@dev",
-		"tracy/tracy": "~2.3",
-		"nette/di": "~2.3"
+		"nette/tester": "~2.0.0",
+		"nette/caching": "~2.2",
+		"nette/di": "~2.3",
+		"phpstan/phpstan-shim": "~0.9.1",
+		"tracy/tracy": "~2.3"
 	},
 	"autoload": {
 		"psr-4": { "Nextras\\Dbal\\": "src/" },
diff --git a/src/Bridges/NetteTracy/ConnectionPanel.php b/src/Bridges/NetteTracy/ConnectionPanel.php
index 81342230..83384ff5 100644
--- a/src/Bridges/NetteTracy/ConnectionPanel.php
+++ b/src/Bridges/NetteTracy/ConnectionPanel.php
@@ -84,9 +84,15 @@ public function getPanel()
 	{
 		$count = $this->count;
 		$queries = $this->queries;
-		$queries = array_map(function($row) {
+		$queries = array_map(function ($row) {
 			try {
-				$row[4] = $this->doExplain ? $this->connection->getDriver()->query('EXPLAIN ' . $row['1'])->fetchAll() : null;
+				$row[4] = null;
+				if ($this->doExplain) {
+					$explain = $this->connection->getDriver()->query('EXPLAIN ' . $row['1']);
+					if ($explain !== null) {
+						$row[4] = $explain->fetchAll();
+					}
+				}
 			} catch (\Throwable $e) {
 				$row[4] = null;
 				$row[3] = null; // rows count is also irrelevant
@@ -109,8 +115,8 @@ public static function highlight($sql)
 		static $keywords2 = 'ALL|DISTINCT|DISTINCTROW|IGNORE|AS|USING|ON|AND|OR|IN|IS|NOT|NULL|[RI]?LIKE|REGEXP|TRUE|FALSE';
 
 		$sql = " $sql ";
-		$sql = htmlSpecialChars($sql, ENT_IGNORE, 'UTF-8');
-		$sql = preg_replace_callback("#(/\\*.+?\\*/)|(?<=[\\s,(])($keywords1)(?=[\\s,)])|(?<=[\\s,(=])($keywords2)(?=[\\s,)=])#is", function($matches) {
+		$sql = htmlspecialchars($sql, ENT_IGNORE, 'UTF-8');
+		$sql = preg_replace_callback("#(/\\*.+?\\*/)|(?<=[\\s,(])($keywords1)(?=[\\s,)])|(?<=[\\s,(=])($keywords2)(?=[\\s,)=])#is", function ($matches) {
 			if (!empty($matches[1])) { // comment
 				return '<em style="color:gray">' . $matches[1] . '</em>';
 			} elseif (!empty($matches[2])) { // most important keywords
diff --git a/src/Drivers/IDriver.php b/src/Drivers/IDriver.php
index e220f046..da0c09a7 100644
--- a/src/Drivers/IDriver.php
+++ b/src/Drivers/IDriver.php
@@ -30,12 +30,14 @@ interface IDriver
 
 	/**
 	 * Connects the driver to database.
+	 * @internal
 	 */
 	public function connect(array $params, callable $loggedQueryCallback);
 
 
 	/**
 	 * Disconnects from the database.
+	 * @internal
 	 */
 	public function disconnect();
 
@@ -54,7 +56,8 @@ public function getResourceHandle();
 
 
 	/**
-	 * Runs query and returns the result. Returns null if query does not select data.
+	 * Runs query and returns a result. Returns a null if the query does not select any data.
+	 * @internal
 	 * @return Result|null
 	 */
 	public function query(string $query);
@@ -62,6 +65,7 @@ public function query(string $query);
 
 	/**
 	 * Returns the last inserted id.
+	 * @internal
 	 * @return mixed
 	 */
 	public function getLastInsertedId(string $sequenceName = null);
@@ -69,6 +73,7 @@ public function getLastInsertedId(string $sequenceName = null);
 
 	/**
 	 * Returns number of affected rows.
+	 * @internal
 	 */
 	public function getAffectedRows(): int;
 
@@ -93,15 +98,20 @@ public function getServerVersion(): string;
 
 	/**
 	 * Pings server.
+	 * @internal
 	 */
 	public function ping(): bool;
 
 
+	/**
+	 * @internal
+	 */
 	public function setTransactionIsolationLevel(int $level);
 
 
 	/**
 	 * Begins a transaction.
+	 * @internal
 	 * @throws DriverException
 	 */
 	public function beginTransaction();
@@ -109,6 +119,7 @@ public function beginTransaction();
 
 	/**
 	 * Commits the current transaction.
+	 * @internal
 	 * @throws DriverException
 	 */
 	public function commitTransaction();
@@ -116,6 +127,7 @@ public function commitTransaction();
 
 	/**
 	 * Rollbacks the current transaction.
+	 * @internal
 	 * @throws DriverException
 	 */
 	public function rollbackTransaction();
@@ -123,6 +135,7 @@ public function rollbackTransaction();
 
 	/**
 	 * Creates a savepoint.
+	 * @internal
 	 * @throws DriverException
 	 * @return void
 	 */
@@ -131,6 +144,7 @@ public function createSavepoint(string $name);
 
 	/**
 	 * Releases the savepoint.
+	 * @internal
 	 * @throws DriverException
 	 */
 	public function releaseSavepoint(string $name);
@@ -138,6 +152,7 @@ public function releaseSavepoint(string $name);
 
 	/**
 	 * Rollbacks the savepoint.
+	 * @internal
 	 * @throws DriverException
 	 */
 	public function rollbackSavepoint(string $name);
diff --git a/src/Drivers/Mysqli/MysqliDriver.php b/src/Drivers/Mysqli/MysqliDriver.php
index b00065c4..652716a3 100644
--- a/src/Drivers/Mysqli/MysqliDriver.php
+++ b/src/Drivers/Mysqli/MysqliDriver.php
@@ -28,7 +28,7 @@
 
 class MysqliDriver implements IDriver
 {
-	/** @var mysqli */
+	/** @var mysqli|null */
 	private $connection;
 
 	/** @var DateTimeZone Timezone for database connection. */
@@ -86,7 +86,10 @@ public function isConnected(): bool
 	}
 
 
-	public function getResourceHandle(): mysqli
+	/**
+	 * @return mysqli|null
+	 */
+	public function getResourceHandle()
 	{
 		return $this->connection;
 	}
@@ -94,6 +97,8 @@ public function getResourceHandle(): mysqli
 
 	public function query(string $query)
 	{
+		assert($this->connection !== null);
+
 		$time = microtime(true);
 		$result = @$this->connection->query($query);
 		$this->timeTaken = microtime(true) - $time;
@@ -117,12 +122,14 @@ public function query(string $query)
 
 	public function getLastInsertedId(string $sequenceName = null)
 	{
+		assert($this->connection !== null);
 		return $this->connection->insert_id;
 	}
 
 
 	public function getAffectedRows(): int
 	{
+		assert($this->connection !== null);
 		return $this->connection->affected_rows;
 	}
 
@@ -141,6 +148,7 @@ public function createPlatform(Connection $connection): IPlatform
 
 	public function getServerVersion(): string
 	{
+		assert($this->connection !== null);
 		$version = $this->connection->server_version;
 		$majorVersion = floor($version / 10000);
 		$minorVersion = floor(($version - $majorVersion * 10000) / 100);
@@ -151,6 +159,7 @@ public function getServerVersion(): string
 
 	public function ping(): bool
 	{
+		assert($this->connection !== null);
 		return $this->connection->ping();
 	}
 
@@ -208,6 +217,8 @@ public function rollbackSavepoint(string $name)
 
 	protected function processInitialSettings(array $params)
 	{
+		assert($this->connection !== null);
+
 		if (isset($params['charset'])) {
 			$charset = $params['charset'];
 		} elseif (($version = $this->getServerVersion()) && version_compare($version, '5.5.3', '>=')) {
@@ -259,6 +270,7 @@ public function convertToPhp(string $value, $nativeType)
 
 	public function convertStringToSql(string $value): string
 	{
+		assert($this->connection !== null);
 		return "'" . $this->connection->escape_string($value) . "'";
 	}
 
@@ -326,6 +338,7 @@ public function convertDateIntervalToSql(\DateInterval $value): string
 
 	public function convertBlobToSql(string $value): string
 	{
+		assert($this->connection !== null);
 		return "_binary'" . $this->connection->escape_string($value) . "'";
 	}
 
diff --git a/src/Drivers/Pgsql/PgsqlDriver.php b/src/Drivers/Pgsql/PgsqlDriver.php
index 88f70c5a..b65bb69b 100644
--- a/src/Drivers/Pgsql/PgsqlDriver.php
+++ b/src/Drivers/Pgsql/PgsqlDriver.php
@@ -27,7 +27,7 @@
 
 class PgsqlDriver implements IDriver
 {
-	/** @var resource */
+	/** @var resource|null */
 	private $connection;
 
 	/** @var DateTimeZone Timezone for database connection. */
diff --git a/src/Drivers/Sqlsrv/SqlsrvDriver.php b/src/Drivers/Sqlsrv/SqlsrvDriver.php
index 6c37724b..6b9ee8c6 100644
--- a/src/Drivers/Sqlsrv/SqlsrvDriver.php
+++ b/src/Drivers/Sqlsrv/SqlsrvDriver.php
@@ -28,7 +28,7 @@
 
 class SqlsrvDriver implements IDriver
 {
-	/** @var resource */
+	/** @var resource|null */
 	private $connection;
 
 	/** @var callable */
@@ -76,7 +76,7 @@ public function connect(array $params, callable $onQueryCallback)
 			}
 		}
 
-		if (isset($connectionInfo['ReturnDatesAsStrings'])) {
+		if (isset($connectionOptions['ReturnDatesAsStrings'])) {
 			throw new NotSupportedException("SqlsrvDriver does not allow to modify 'ReturnDatesAsStrings' parameter.");
 		}
 		$connectionOptions['ReturnDatesAsStrings'] = true;
diff --git a/src/Drivers/Sqlsrv/SqlsrvResultAdapter.php b/src/Drivers/Sqlsrv/SqlsrvResultAdapter.php
index 06685b26..fb277112 100644
--- a/src/Drivers/Sqlsrv/SqlsrvResultAdapter.php
+++ b/src/Drivers/Sqlsrv/SqlsrvResultAdapter.php
@@ -26,7 +26,7 @@ class SqlsrvResultAdapter implements IResultAdapter
 		SqlsrvResultTypes::TYPE_DATETIMEOFFSET                    => self::TYPE_DRIVER_SPECIFIC,
 	];
 
-	/** @var int */
+	/** @var int|null */
 	private $index;
 
 	/** @var resource */
diff --git a/src/QueryBuilder/QueryBuilder.php b/src/QueryBuilder/QueryBuilder.php
index c85bcc20..b7a42b73 100644
--- a/src/QueryBuilder/QueryBuilder.php
+++ b/src/QueryBuilder/QueryBuilder.php
@@ -47,13 +47,13 @@ class QueryBuilder
 	/** @var array|null */
 	private $join;
 
-	/** @var array|null */
+	/** @var string|null */
 	private $where;
 
 	/** @var array|null */
 	private $group;
 
-	/** @var array|null */
+	/** @var string|null */
 	private $having;
 
 	/** @var array|null */
@@ -62,7 +62,7 @@ class QueryBuilder
 	/** @var array|null */
 	private $limit;
 
-	/** @var string */
+	/** @var string|null */
 	private $generatedSql;
 
 
@@ -263,9 +263,6 @@ public function andWhere(string $expression, ...$args): self
 
 	/**
 	 * Adds expression with OR to WHERE clause.
-	 * @param  string $expression
-	 * @param  mixed ...$arg
-	 * @return self
 	 */
 	public function orWhere(string $expression, ...$args): self
 	{