diff --git a/UPGRADE.md b/UPGRADE.md
index 24917ec6e71..57b320f7069 100644
--- a/UPGRADE.md
+++ b/UPGRADE.md
@@ -1,5 +1,11 @@
 # Upgrade to 3.0
 
+## BC BREAK: Changes in the `Doctrine\DBAL\Event` API
+
+- `SchemaAlterTableAddColumnEventArgs::addSql()` and the same method in other `SchemaEventArgs`-based classes no longer accept an array of SQL statements. They accept a variadic string.
+- `ConnectionEventArgs::getDriver()`, `::getDatabasePlatform()` and `::getSchemaManager()` methods have been removed. The connection information can be obtained from the connection which is available via `::getConnection()`.
+- `SchemaColumnDefinitionEventArgs::getDatabasePlatform()` and `SchemaIndexDefinitionEventArgs::getDatabasePlatform()` have been removed for the same reason as above.
+
 ## BC BREAK: Changes in the `Doctrine\DBAL\Connection` API
 
 - The following methods have been removed as leaking internal implementation details: `::getHost()`, `::getPort()`, `::getUsername()`, `::getPassword()`.
diff --git a/lib/Doctrine/DBAL/Event/ConnectionEventArgs.php b/lib/Doctrine/DBAL/Event/ConnectionEventArgs.php
index 8c40a3bfae3..38d0b26f537 100644
--- a/lib/Doctrine/DBAL/Event/ConnectionEventArgs.php
+++ b/lib/Doctrine/DBAL/Event/ConnectionEventArgs.php
@@ -6,9 +6,6 @@
 
 use Doctrine\Common\EventArgs;
 use Doctrine\DBAL\Connection;
-use Doctrine\DBAL\Driver;
-use Doctrine\DBAL\Platforms\AbstractPlatform;
-use Doctrine\DBAL\Schema\AbstractSchemaManager;
 
 /**
  * Event Arguments used when a Driver connection is established inside Doctrine\DBAL\Connection.
@@ -23,35 +20,8 @@ public function __construct(Connection $connection)
         $this->connection = $connection;
     }
 
-    /**
-     * @return Connection
-     */
-    public function getConnection()
+    public function getConnection() : Connection
     {
         return $this->connection;
     }
-
-    /**
-     * @return Driver
-     */
-    public function getDriver()
-    {
-        return $this->connection->getDriver();
-    }
-
-    /**
-     * @return AbstractPlatform
-     */
-    public function getDatabasePlatform()
-    {
-        return $this->connection->getDatabasePlatform();
-    }
-
-    /**
-     * @return AbstractSchemaManager
-     */
-    public function getSchemaManager()
-    {
-        return $this->connection->getSchemaManager();
-    }
 }
diff --git a/lib/Doctrine/DBAL/Event/Listeners/OracleSessionInit.php b/lib/Doctrine/DBAL/Event/Listeners/OracleSessionInit.php
index 413f9c6df16..fcd2e01f977 100644
--- a/lib/Doctrine/DBAL/Event/Listeners/OracleSessionInit.php
+++ b/lib/Doctrine/DBAL/Event/Listeners/OracleSessionInit.php
@@ -25,7 +25,7 @@
  */
 class OracleSessionInit implements EventSubscriber
 {
-    /** @var string[] */
+    /** @var array<string, string> */
     protected $_defaultSessionVars = [
         'NLS_TIME_FORMAT' => 'HH24:MI:SS',
         'NLS_DATE_FORMAT' => 'YYYY-MM-DD HH24:MI:SS',
@@ -35,17 +35,14 @@ class OracleSessionInit implements EventSubscriber
     ];
 
     /**
-     * @param string[] $oracleSessionVars
+     * @param array<string, string> $oracleSessionVars
      */
     public function __construct(array $oracleSessionVars = [])
     {
         $this->_defaultSessionVars = array_merge($this->_defaultSessionVars, $oracleSessionVars);
     }
 
-    /**
-     * @return void
-     */
-    public function postConnect(ConnectionEventArgs $args)
+    public function postConnect(ConnectionEventArgs $args) : void
     {
         if (! count($this->_defaultSessionVars)) {
             return;
@@ -67,7 +64,7 @@ public function postConnect(ConnectionEventArgs $args)
     /**
      * {@inheritdoc}
      */
-    public function getSubscribedEvents()
+    public function getSubscribedEvents() : array
     {
         return [Events::postConnect];
     }
diff --git a/lib/Doctrine/DBAL/Event/Listeners/SQLSessionInit.php b/lib/Doctrine/DBAL/Event/Listeners/SQLSessionInit.php
index 629e0f43cd8..e1eee9840ef 100644
--- a/lib/Doctrine/DBAL/Event/Listeners/SQLSessionInit.php
+++ b/lib/Doctrine/DBAL/Event/Listeners/SQLSessionInit.php
@@ -16,18 +16,12 @@ class SQLSessionInit implements EventSubscriber
     /** @var string */
     protected $sql;
 
-    /**
-     * @param string $sql
-     */
-    public function __construct($sql)
+    public function __construct(string $sql)
     {
         $this->sql = $sql;
     }
 
-    /**
-     * @return void
-     */
-    public function postConnect(ConnectionEventArgs $args)
+    public function postConnect(ConnectionEventArgs $args) : void
     {
         $conn = $args->getConnection();
         $conn->exec($this->sql);
@@ -36,7 +30,7 @@ public function postConnect(ConnectionEventArgs $args)
     /**
      * {@inheritdoc}
      */
-    public function getSubscribedEvents()
+    public function getSubscribedEvents() : array
     {
         return [Events::postConnect];
     }
diff --git a/lib/Doctrine/DBAL/Event/SchemaAlterTableAddColumnEventArgs.php b/lib/Doctrine/DBAL/Event/SchemaAlterTableAddColumnEventArgs.php
index 9799e9b4e59..8d12d74cc48 100644
--- a/lib/Doctrine/DBAL/Event/SchemaAlterTableAddColumnEventArgs.php
+++ b/lib/Doctrine/DBAL/Event/SchemaAlterTableAddColumnEventArgs.php
@@ -8,7 +8,6 @@
 use Doctrine\DBAL\Schema\Column;
 use Doctrine\DBAL\Schema\TableDiff;
 use function array_merge;
-use function is_array;
 
 /**
  * Event Arguments used when SQL queries for adding table columns are generated inside Doctrine\DBAL\Platform\*Platform.
@@ -24,7 +23,7 @@ class SchemaAlterTableAddColumnEventArgs extends SchemaEventArgs
     /** @var AbstractPlatform */
     private $platform;
 
-    /** @var string[] */
+    /** @var array<int, string> */
     private $sql = [];
 
     public function __construct(Column $column, TableDiff $tableDiff, AbstractPlatform $platform)
@@ -34,50 +33,35 @@ public function __construct(Column $column, TableDiff $tableDiff, AbstractPlatfo
         $this->platform  = $platform;
     }
 
-    /**
-     * @return Column
-     */
-    public function getColumn()
+    public function getColumn() : Column
     {
         return $this->column;
     }
 
-    /**
-     * @return TableDiff
-     */
-    public function getTableDiff()
+    public function getTableDiff() : TableDiff
     {
         return $this->tableDiff;
     }
 
-    /**
-     * @return AbstractPlatform
-     */
-    public function getPlatform()
+    public function getPlatform() : AbstractPlatform
     {
         return $this->platform;
     }
 
     /**
-     * @param string|string[] $sql
-     *
-     * @return \Doctrine\DBAL\Event\SchemaAlterTableAddColumnEventArgs
+     * @return $this
      */
-    public function addSql($sql)
+    public function addSql(string ...$sql) : self
     {
-        if (is_array($sql)) {
-            $this->sql = array_merge($this->sql, $sql);
-        } else {
-            $this->sql[] = $sql;
-        }
+        $this->sql = array_merge($this->sql, $sql);
 
         return $this;
     }
 
     /**
-     * @return string[]
+     * @return array<int, string>
      */
-    public function getSql()
+    public function getSql() : array
     {
         return $this->sql;
     }
diff --git a/lib/Doctrine/DBAL/Event/SchemaAlterTableChangeColumnEventArgs.php b/lib/Doctrine/DBAL/Event/SchemaAlterTableChangeColumnEventArgs.php
index 33f2fac5fe9..cc3019d4faf 100644
--- a/lib/Doctrine/DBAL/Event/SchemaAlterTableChangeColumnEventArgs.php
+++ b/lib/Doctrine/DBAL/Event/SchemaAlterTableChangeColumnEventArgs.php
@@ -8,7 +8,6 @@
 use Doctrine\DBAL\Schema\ColumnDiff;
 use Doctrine\DBAL\Schema\TableDiff;
 use function array_merge;
-use function is_array;
 
 /**
  * Event Arguments used when SQL queries for changing table columns are generated inside Doctrine\DBAL\Platform\*Platform.
@@ -24,7 +23,7 @@ class SchemaAlterTableChangeColumnEventArgs extends SchemaEventArgs
     /** @var AbstractPlatform */
     private $platform;
 
-    /** @var string[] */
+    /** @var array<int, string> */
     private $sql = [];
 
     public function __construct(ColumnDiff $columnDiff, TableDiff $tableDiff, AbstractPlatform $platform)
@@ -34,50 +33,35 @@ public function __construct(ColumnDiff $columnDiff, TableDiff $tableDiff, Abstra
         $this->platform   = $platform;
     }
 
-    /**
-     * @return ColumnDiff
-     */
-    public function getColumnDiff()
+    public function getColumnDiff() : ColumnDiff
     {
         return $this->columnDiff;
     }
 
-    /**
-     * @return TableDiff
-     */
-    public function getTableDiff()
+    public function getTableDiff() : TableDiff
     {
         return $this->tableDiff;
     }
 
-    /**
-     * @return AbstractPlatform
-     */
-    public function getPlatform()
+    public function getPlatform() : AbstractPlatform
     {
         return $this->platform;
     }
 
     /**
-     * @param string|string[] $sql
-     *
-     * @return \Doctrine\DBAL\Event\SchemaAlterTableChangeColumnEventArgs
+     * @return $this
      */
-    public function addSql($sql)
+    public function addSql(string ...$sql) : self
     {
-        if (is_array($sql)) {
-            $this->sql = array_merge($this->sql, $sql);
-        } else {
-            $this->sql[] = $sql;
-        }
+        $this->sql = array_merge($this->sql, $sql);
 
         return $this;
     }
 
     /**
-     * @return string[]
+     * @return array<int, string>
      */
-    public function getSql()
+    public function getSql() : array
     {
         return $this->sql;
     }
diff --git a/lib/Doctrine/DBAL/Event/SchemaAlterTableEventArgs.php b/lib/Doctrine/DBAL/Event/SchemaAlterTableEventArgs.php
index 35258004fb9..910b4827232 100644
--- a/lib/Doctrine/DBAL/Event/SchemaAlterTableEventArgs.php
+++ b/lib/Doctrine/DBAL/Event/SchemaAlterTableEventArgs.php
@@ -7,7 +7,6 @@
 use Doctrine\DBAL\Platforms\AbstractPlatform;
 use Doctrine\DBAL\Schema\TableDiff;
 use function array_merge;
-use function is_array;
 
 /**
  * Event Arguments used when SQL queries for creating tables are generated inside Doctrine\DBAL\Platform\*Platform.
@@ -20,7 +19,7 @@ class SchemaAlterTableEventArgs extends SchemaEventArgs
     /** @var AbstractPlatform */
     private $platform;
 
-    /** @var string[] */
+    /** @var array<int, string> */
     private $sql = [];
 
     public function __construct(TableDiff $tableDiff, AbstractPlatform $platform)
@@ -29,42 +28,30 @@ public function __construct(TableDiff $tableDiff, AbstractPlatform $platform)
         $this->platform  = $platform;
     }
 
-    /**
-     * @return TableDiff
-     */
-    public function getTableDiff()
+    public function getTableDiff() : TableDiff
     {
         return $this->tableDiff;
     }
 
-    /**
-     * @return AbstractPlatform
-     */
-    public function getPlatform()
+    public function getPlatform() : AbstractPlatform
     {
         return $this->platform;
     }
 
     /**
-     * @param string|string[] $sql
-     *
-     * @return \Doctrine\DBAL\Event\SchemaAlterTableEventArgs
+     * @return $this
      */
-    public function addSql($sql)
+    public function addSql(string ...$sql) : self
     {
-        if (is_array($sql)) {
-            $this->sql = array_merge($this->sql, $sql);
-        } else {
-            $this->sql[] = $sql;
-        }
+        $this->sql = array_merge($this->sql, $sql);
 
         return $this;
     }
 
     /**
-     * @return string[]
+     * @return array<int, string>
      */
-    public function getSql()
+    public function getSql() : array
     {
         return $this->sql;
     }
diff --git a/lib/Doctrine/DBAL/Event/SchemaAlterTableRemoveColumnEventArgs.php b/lib/Doctrine/DBAL/Event/SchemaAlterTableRemoveColumnEventArgs.php
index 80daf00fe07..06dd5641b74 100644
--- a/lib/Doctrine/DBAL/Event/SchemaAlterTableRemoveColumnEventArgs.php
+++ b/lib/Doctrine/DBAL/Event/SchemaAlterTableRemoveColumnEventArgs.php
@@ -8,7 +8,6 @@
 use Doctrine\DBAL\Schema\Column;
 use Doctrine\DBAL\Schema\TableDiff;
 use function array_merge;
-use function is_array;
 
 /**
  * Event Arguments used when SQL queries for removing table columns are generated inside Doctrine\DBAL\Platform\*Platform.
@@ -24,7 +23,7 @@ class SchemaAlterTableRemoveColumnEventArgs extends SchemaEventArgs
     /** @var AbstractPlatform */
     private $platform;
 
-    /** @var string[] */
+    /** @var array<int, string> */
     private $sql = [];
 
     public function __construct(Column $column, TableDiff $tableDiff, AbstractPlatform $platform)
@@ -34,50 +33,35 @@ public function __construct(Column $column, TableDiff $tableDiff, AbstractPlatfo
         $this->platform  = $platform;
     }
 
-    /**
-     * @return Column
-     */
-    public function getColumn()
+    public function getColumn() : Column
     {
         return $this->column;
     }
 
-    /**
-     * @return TableDiff
-     */
-    public function getTableDiff()
+    public function getTableDiff() : TableDiff
     {
         return $this->tableDiff;
     }
 
-    /**
-     * @return AbstractPlatform
-     */
-    public function getPlatform()
+    public function getPlatform() : AbstractPlatform
     {
         return $this->platform;
     }
 
     /**
-     * @param string|string[] $sql
-     *
-     * @return \Doctrine\DBAL\Event\SchemaAlterTableRemoveColumnEventArgs
+     * @return $this
      */
-    public function addSql($sql)
+    public function addSql(string ...$sql) : self
     {
-        if (is_array($sql)) {
-            $this->sql = array_merge($this->sql, $sql);
-        } else {
-            $this->sql[] = $sql;
-        }
+        $this->sql = array_merge($this->sql, $sql);
 
         return $this;
     }
 
     /**
-     * @return string[]
+     * @return array<int, string>
      */
-    public function getSql()
+    public function getSql() : array
     {
         return $this->sql;
     }
diff --git a/lib/Doctrine/DBAL/Event/SchemaAlterTableRenameColumnEventArgs.php b/lib/Doctrine/DBAL/Event/SchemaAlterTableRenameColumnEventArgs.php
index 49f7615c76e..8f9059b119a 100644
--- a/lib/Doctrine/DBAL/Event/SchemaAlterTableRenameColumnEventArgs.php
+++ b/lib/Doctrine/DBAL/Event/SchemaAlterTableRenameColumnEventArgs.php
@@ -8,7 +8,6 @@
 use Doctrine\DBAL\Schema\Column;
 use Doctrine\DBAL\Schema\TableDiff;
 use function array_merge;
-use function is_array;
 
 /**
  * Event Arguments used when SQL queries for renaming table columns are generated inside Doctrine\DBAL\Platform\*Platform.
@@ -27,13 +26,10 @@ class SchemaAlterTableRenameColumnEventArgs extends SchemaEventArgs
     /** @var AbstractPlatform */
     private $platform;
 
-    /** @var string[] */
+    /** @var array<int, string> */
     private $sql = [];
 
-    /**
-     * @param string $oldColumnName
-     */
-    public function __construct($oldColumnName, Column $column, TableDiff $tableDiff, AbstractPlatform $platform)
+    public function __construct(string $oldColumnName, Column $column, TableDiff $tableDiff, AbstractPlatform $platform)
     {
         $this->oldColumnName = $oldColumnName;
         $this->column        = $column;
@@ -41,58 +37,40 @@ public function __construct($oldColumnName, Column $column, TableDiff $tableDiff
         $this->platform      = $platform;
     }
 
-    /**
-     * @return string
-     */
-    public function getOldColumnName()
+    public function getOldColumnName() : string
     {
         return $this->oldColumnName;
     }
 
-    /**
-     * @return Column
-     */
-    public function getColumn()
+    public function getColumn() : Column
     {
         return $this->column;
     }
 
-    /**
-     * @return TableDiff
-     */
-    public function getTableDiff()
+    public function getTableDiff() : TableDiff
     {
         return $this->tableDiff;
     }
 
-    /**
-     * @return AbstractPlatform
-     */
-    public function getPlatform()
+    public function getPlatform() : AbstractPlatform
     {
         return $this->platform;
     }
 
     /**
-     * @param string|string[] $sql
-     *
-     * @return \Doctrine\DBAL\Event\SchemaAlterTableRenameColumnEventArgs
+     * @return $this
      */
-    public function addSql($sql)
+    public function addSql(string ...$sql) : self
     {
-        if (is_array($sql)) {
-            $this->sql = array_merge($this->sql, $sql);
-        } else {
-            $this->sql[] = $sql;
-        }
+        $this->sql = array_merge($this->sql, $sql);
 
         return $this;
     }
 
     /**
-     * @return string[]
+     * @return array<int, string>
      */
-    public function getSql()
+    public function getSql() : array
     {
         return $this->sql;
     }
diff --git a/lib/Doctrine/DBAL/Event/SchemaColumnDefinitionEventArgs.php b/lib/Doctrine/DBAL/Event/SchemaColumnDefinitionEventArgs.php
index 9e51b1038f0..36041797458 100644
--- a/lib/Doctrine/DBAL/Event/SchemaColumnDefinitionEventArgs.php
+++ b/lib/Doctrine/DBAL/Event/SchemaColumnDefinitionEventArgs.php
@@ -5,7 +5,6 @@
 namespace Doctrine\DBAL\Event;
 
 use Doctrine\DBAL\Connection;
-use Doctrine\DBAL\Platforms\AbstractPlatform;
 use Doctrine\DBAL\Schema\Column;
 
 /**
@@ -14,12 +13,12 @@
 class SchemaColumnDefinitionEventArgs extends SchemaEventArgs
 {
     /** @var Column|null */
-    private $column = null;
+    private $column;
 
     /**
      * Raw column data as fetched from the database.
      *
-     * @var mixed[]
+     * @var array<string, mixed>
      */
     private $tableColumn;
 
@@ -33,11 +32,9 @@ class SchemaColumnDefinitionEventArgs extends SchemaEventArgs
     private $connection;
 
     /**
-     * @param mixed[] $tableColumn
-     * @param string  $table
-     * @param string  $database
+     * @param array<string, mixed> $tableColumn
      */
-    public function __construct(array $tableColumn, $table, $database, Connection $connection)
+    public function __construct(array $tableColumn, string $table, string $database, Connection $connection)
     {
         $this->tableColumn = $tableColumn;
         $this->table       = $table;
@@ -49,60 +46,40 @@ public function __construct(array $tableColumn, $table, $database, Connection $c
      * Allows to clear the column which means the column will be excluded from
      * tables column list.
      *
-     * @return \Doctrine\DBAL\Event\SchemaColumnDefinitionEventArgs
+     * @return $this
      */
-    public function setColumn(?Column $column = null)
+    public function setColumn(?Column $column) : self
     {
         $this->column = $column;
 
         return $this;
     }
 
-    /**
-     * @return Column|null
-     */
-    public function getColumn()
+    public function getColumn() : ?Column
     {
         return $this->column;
     }
 
     /**
-     * @return mixed[]
+     * @return array<string, mixed>
      */
-    public function getTableColumn()
+    public function getTableColumn() : array
     {
         return $this->tableColumn;
     }
 
-    /**
-     * @return string
-     */
-    public function getTable()
+    public function getTable() : string
     {
         return $this->table;
     }
 
-    /**
-     * @return string
-     */
-    public function getDatabase()
+    public function getDatabase() : string
     {
         return $this->database;
     }
 
-    /**
-     * @return Connection
-     */
-    public function getConnection()
+    public function getConnection() : Connection
     {
         return $this->connection;
     }
-
-    /**
-     * @return AbstractPlatform
-     */
-    public function getDatabasePlatform()
-    {
-        return $this->connection->getDatabasePlatform();
-    }
 }
diff --git a/lib/Doctrine/DBAL/Event/SchemaCreateTableColumnEventArgs.php b/lib/Doctrine/DBAL/Event/SchemaCreateTableColumnEventArgs.php
index f4e70e0ff89..038da6a0a68 100644
--- a/lib/Doctrine/DBAL/Event/SchemaCreateTableColumnEventArgs.php
+++ b/lib/Doctrine/DBAL/Event/SchemaCreateTableColumnEventArgs.php
@@ -7,7 +7,7 @@
 use Doctrine\DBAL\Platforms\AbstractPlatform;
 use Doctrine\DBAL\Schema\Column;
 use Doctrine\DBAL\Schema\Table;
-use function is_array;
+use function array_merge;
 
 /**
  * Event Arguments used when SQL queries for creating table columns are generated inside Doctrine\DBAL\Platform\AbstractPlatform.
@@ -33,44 +33,27 @@ public function __construct(Column $column, Table $table, AbstractPlatform $plat
         $this->platform = $platform;
     }
 
-    /**
-     * @return Column
-     */
-    public function getColumn()
+    public function getColumn() : Column
     {
         return $this->column;
     }
 
-    /**
-     * @return Table
-     */
-    public function getTable()
+    public function getTable() : Table
     {
         return $this->table;
     }
 
-    /**
-     * @return AbstractPlatform
-     */
-    public function getPlatform()
+    public function getPlatform() : AbstractPlatform
     {
         return $this->platform;
     }
 
     /**
-     * @param string|string[] $sql
-     *
-     * @return \Doctrine\DBAL\Event\SchemaCreateTableColumnEventArgs
+     * @return $this
      */
-    public function addSql($sql)
+    public function addSql(string ...$sql) : self
     {
-        if (is_array($sql)) {
-            foreach ($sql as $query) {
-                $this->sql[] = $query;
-            }
-        } else {
-            $this->sql[] = $sql;
-        }
+        $this->sql = array_merge($this->sql, $sql);
 
         return $this;
     }
@@ -78,7 +61,7 @@ public function addSql($sql)
     /**
      * @return array<int, string>
      */
-    public function getSql()
+    public function getSql() : array
     {
         return $this->sql;
     }
diff --git a/lib/Doctrine/DBAL/Event/SchemaCreateTableEventArgs.php b/lib/Doctrine/DBAL/Event/SchemaCreateTableEventArgs.php
index 5046add54c3..b59f3470acb 100644
--- a/lib/Doctrine/DBAL/Event/SchemaCreateTableEventArgs.php
+++ b/lib/Doctrine/DBAL/Event/SchemaCreateTableEventArgs.php
@@ -6,7 +6,7 @@
 
 use Doctrine\DBAL\Platforms\AbstractPlatform;
 use Doctrine\DBAL\Schema\Table;
-use function is_array;
+use function array_merge;
 
 /**
  * Event Arguments used when SQL queries for creating tables are generated inside Doctrine\DBAL\Platform\AbstractPlatform.
@@ -16,21 +16,21 @@ class SchemaCreateTableEventArgs extends SchemaEventArgs
     /** @var Table */
     private $table;
 
-    /** @var mixed[][] */
+    /** @var array<string, array<string, mixed>> */
     private $columns;
 
-    /** @var mixed[] */
+    /** @var array<string, mixed> */
     private $options;
 
     /** @var AbstractPlatform */
     private $platform;
 
-    /** @var string[] */
+    /** @var array<int, string> */
     private $sql = [];
 
     /**
-     * @param mixed[][] $columns
-     * @param mixed[]   $options
+     * @param array<string, array<string, mixed>> $columns
+     * @param array<string, mixed>                $options
      */
     public function __construct(Table $table, array $columns, array $options, AbstractPlatform $platform)
     {
@@ -40,52 +40,38 @@ public function __construct(Table $table, array $columns, array $options, Abstra
         $this->platform = $platform;
     }
 
-    /**
-     * @return Table
-     */
-    public function getTable()
+    public function getTable() : Table
     {
         return $this->table;
     }
 
     /**
-     * @return mixed[][]
+     * @return array<string, array<string, mixed>>
      */
-    public function getColumns()
+    public function getColumns() : array
     {
         return $this->columns;
     }
 
     /**
-     * @return mixed[]
+     * @return array<string, mixed>
      */
-    public function getOptions()
+    public function getOptions() : array
     {
         return $this->options;
     }
 
-    /**
-     * @return AbstractPlatform
-     */
-    public function getPlatform()
+    public function getPlatform() : AbstractPlatform
     {
         return $this->platform;
     }
 
     /**
-     * @param string|string[] $sql
-     *
-     * @return \Doctrine\DBAL\Event\SchemaCreateTableEventArgs
+     * @return $this
      */
-    public function addSql($sql)
+    public function addSql(string ...$sql) : self
     {
-        if (is_array($sql)) {
-            foreach ($sql as $query) {
-                $this->sql[] = $query;
-            }
-        } else {
-            $this->sql[] = $sql;
-        }
+        $this->sql = array_merge($this->sql, $sql);
 
         return $this;
     }
@@ -93,7 +79,7 @@ public function addSql($sql)
     /**
      * @return array<int, string>
      */
-    public function getSql()
+    public function getSql() : array
     {
         return $this->sql;
     }
diff --git a/lib/Doctrine/DBAL/Event/SchemaDropTableEventArgs.php b/lib/Doctrine/DBAL/Event/SchemaDropTableEventArgs.php
index 9d21bd35e0e..73fe78201cd 100644
--- a/lib/Doctrine/DBAL/Event/SchemaDropTableEventArgs.php
+++ b/lib/Doctrine/DBAL/Event/SchemaDropTableEventArgs.php
@@ -41,30 +41,22 @@ public function getTable()
         return $this->table;
     }
 
-    /**
-     * @return AbstractPlatform
-     */
-    public function getPlatform()
+    public function getPlatform() : AbstractPlatform
     {
         return $this->platform;
     }
 
     /**
-     * @param string $sql
-     *
-     * @return \Doctrine\DBAL\Event\SchemaDropTableEventArgs
+     * @return $this
      */
-    public function setSql($sql)
+    public function setSql(string $sql) : self
     {
         $this->sql = $sql;
 
         return $this;
     }
 
-    /**
-     * @return string|null
-     */
-    public function getSql()
+    public function getSql() : ?string
     {
         return $this->sql;
     }
diff --git a/lib/Doctrine/DBAL/Event/SchemaEventArgs.php b/lib/Doctrine/DBAL/Event/SchemaEventArgs.php
index a5c152872b8..4b15c80e444 100644
--- a/lib/Doctrine/DBAL/Event/SchemaEventArgs.php
+++ b/lib/Doctrine/DBAL/Event/SchemaEventArgs.php
@@ -15,19 +15,16 @@ class SchemaEventArgs extends EventArgs
     private $preventDefault = false;
 
     /**
-     * @return \Doctrine\DBAL\Event\SchemaEventArgs
+     * @return $this
      */
-    public function preventDefault()
+    public function preventDefault() : self
     {
         $this->preventDefault = true;
 
         return $this;
     }
 
-    /**
-     * @return bool
-     */
-    public function isDefaultPrevented()
+    public function isDefaultPrevented() : bool
     {
         return $this->preventDefault;
     }
diff --git a/lib/Doctrine/DBAL/Event/SchemaIndexDefinitionEventArgs.php b/lib/Doctrine/DBAL/Event/SchemaIndexDefinitionEventArgs.php
index bfbd8cfe619..c39e1f3b2ea 100644
--- a/lib/Doctrine/DBAL/Event/SchemaIndexDefinitionEventArgs.php
+++ b/lib/Doctrine/DBAL/Event/SchemaIndexDefinitionEventArgs.php
@@ -5,7 +5,6 @@
 namespace Doctrine\DBAL\Event;
 
 use Doctrine\DBAL\Connection;
-use Doctrine\DBAL\Platforms\AbstractPlatform;
 use Doctrine\DBAL\Schema\Index;
 
 /**
@@ -14,12 +13,12 @@
 class SchemaIndexDefinitionEventArgs extends SchemaEventArgs
 {
     /** @var Index|null */
-    private $index = null;
+    private $index;
 
     /**
      * Raw index data as fetched from the database.
      *
-     * @var mixed[]
+     * @var array<string, mixed>
      */
     private $tableIndex;
 
@@ -30,10 +29,9 @@ class SchemaIndexDefinitionEventArgs extends SchemaEventArgs
     private $connection;
 
     /**
-     * @param mixed[] $tableIndex
-     * @param string  $table
+     * @param array<string, mixed> $tableIndex
      */
-    public function __construct(array $tableIndex, $table, Connection $connection)
+    public function __construct(array $tableIndex, string $table, Connection $connection)
     {
         $this->tableIndex = $tableIndex;
         $this->table      = $table;
@@ -43,52 +41,35 @@ public function __construct(array $tableIndex, $table, Connection $connection)
     /**
      * Allows to clear the index which means the index will be excluded from tables index list.
      *
-     * @return SchemaIndexDefinitionEventArgs
+     * @return $this
      */
-    public function setIndex(?Index $index = null)
+    public function setIndex(?Index $index) : self
     {
         $this->index = $index;
 
         return $this;
     }
 
-    /**
-     * @return Index|null
-     */
-    public function getIndex()
+    public function getIndex() : ?Index
     {
         return $this->index;
     }
 
     /**
-     * @return mixed[]
+     * @return array<string, mixed>
      */
-    public function getTableIndex()
+    public function getTableIndex() : array
     {
         return $this->tableIndex;
     }
 
-    /**
-     * @return string
-     */
-    public function getTable()
+    public function getTable() : string
     {
         return $this->table;
     }
 
-    /**
-     * @return Connection
-     */
-    public function getConnection()
+    public function getConnection() : Connection
     {
         return $this->connection;
     }
-
-    /**
-     * @return AbstractPlatform
-     */
-    public function getDatabasePlatform()
-    {
-        return $this->connection->getDatabasePlatform();
-    }
 }
diff --git a/lib/Doctrine/DBAL/Platforms/AbstractPlatform.php b/lib/Doctrine/DBAL/Platforms/AbstractPlatform.php
index 4522a391cf3..a52e885e091 100644
--- a/lib/Doctrine/DBAL/Platforms/AbstractPlatform.php
+++ b/lib/Doctrine/DBAL/Platforms/AbstractPlatform.php
@@ -1345,7 +1345,10 @@ public function getCreateTableSQL(Table $table, int $createFlags = self::CREATE_
                 $columnData['primary'] = true;
             }
 
-            $columns[$columnData['name']] = $columnData;
+            $columnName = $columnData['name'];
+            assert(is_string($columnName));
+
+            $columns[$columnName] = $columnData;
         }
 
         if ($this->_eventManager !== null && $this->_eventManager->hasListeners(Events::onSchemaCreateTable)) {