diff --git a/core/lib/Drupal/Core/Database/Driver/pgsql/Connection.php b/core/lib/Drupal/Core/Database/Driver/pgsql/Connection.php
index 7e1c358..e059c1d 100644
--- a/core/lib/Drupal/Core/Database/Driver/pgsql/Connection.php
+++ b/core/lib/Drupal/Core/Database/Driver/pgsql/Connection.php
@@ -22,7 +22,7 @@
 class Connection extends DatabaseConnection {
 
   /**
-   * The name by which to obtain a lock for retrieve the next insert id.
+   * The name by which to obtain a lock for retrieve the next insert ID.
    */
   const POSTGRESQL_NEXTID_LOCK = 1000;
 
@@ -240,19 +240,19 @@ public function mapConditionOperator($operator) {
   }
 
   /**
-   * Retrieve the next id in a sequence.
+   * Retrieve the next ID in a sequence.
    *
    * PostgreSQL has built in sequences. We'll use these instead of inserting
    * and updating a sequences table.
    *
    * @param $existing
-   *   After a database import, it might be that the sequences table is behind,
-   *   so by passing in the maximum existing id, it can be assured that we
-   *   never issue the same id.
+   *   The maximum existing ID makes sure that we never issue the same ID, even
+   *   after a database import when it might be that the sequences table is
+   *   behind.
    *
    * @return
    *   An integer number larger than any number returned by earlier calls and
-   *   also larger than the $existing if one was passed in.
+   *   also larger than $existing if one was passed in.
    */
   public function nextId($existing = 0) {
 
@@ -280,10 +280,10 @@ public function nextId($existing = 0) {
       return $id;
     }
 
-    // Reset the sequence to a higher value than the existing id.
+    // Reset the sequence to a higher value than the existing ID.
     $this->query("ALTER SEQUENCE " . $sequence_name . " RESTART WITH " . ($existing + 1));
 
-    // Retrieve the next id. We know this will be as high as we want it.
+    // Retrieve the next ID. We know this will be as high as we want it.
     $id = $this->query("SELECT nextval('" . $sequence_name . "')")->fetchField();
 
     $this->query("SELECT pg_advisory_unlock(" . self::POSTGRESQL_NEXTID_LOCK . ")");
diff --git a/core/lib/Drupal/Core/Database/Driver/pgsql/Schema.php b/core/lib/Drupal/Core/Database/Driver/pgsql/Schema.php
index 83a94de..4bb4c54 100644
--- a/core/lib/Drupal/Core/Database/Driver/pgsql/Schema.php
+++ b/core/lib/Drupal/Core/Database/Driver/pgsql/Schema.php
@@ -87,7 +87,7 @@ protected function ensureIdentifiersLength($identifier) {
    * @param string $table
    *   The non-prefixed name of the table.
    *
-   * @return \stdClass
+   * @return object
    *   An object with two member variables:
    *     - 'blob_fields' that lists all the blob fields in the table.
    *     - 'sequences' that lists the sequences used in that table.
@@ -379,13 +379,15 @@ function getFieldTypeMap() {
   }
 
   /**
+   * Generates SQL from field definitions.
+   *
    * @param array $fields
-   *   Array of field definitions. Each array value is either
-   *   - a field name (string), or
+   *   Array of field definitions. Each array value is either:
+   *   - a field name (string),
    *   - an array of two strings, array($field_name, $alias).
    *
    * @return string
-   *   The Generated SQL snippet.
+   *   The generated SQL snippet.
    */
   protected function _createKeySql($fields) {
     $return = array();
@@ -454,7 +456,9 @@ public function copyTable($source, $destination) {
     //   table_name + constraint name convention anymore.
     throw new \Exception('Not implemented, see https://drupal.org/node/2061879');
   }
-
+  /**
+  * {@inheritdoc}
+  */
   public function dropTable($table) {
     if (!$this->tableExists($table)) {
       return FALSE;
@@ -719,7 +723,7 @@ public function changeField($table, $field, $field_new, $spec, $new_keys = array
    *   - an array of two strings, array($field_name, $alias).
    *
    * @return string
-   *   The Generated SQL snippet.
+   *   The generated SQL snippet.
    */
   protected function _createIndexSql($table, $name, $fields) {
     $query = 'CREATE INDEX "' . $this->ensureIdentifiersLength($table, $name, 'idx') . '" ON {' . $table . '} (';
@@ -745,10 +749,11 @@ protected function _createKeys($table, $new_keys) {
 
   /**
    * Retrieve a table or column comment.
+   *
    * @param $table
-   *   The database table whose comments to return.
+   *   The database table to return comments for.
    * @param $column
-   *   (optional) A column in $table whose comments to return.
+   *   (optional) A column in $table to return comments for.
    */
   public function getComment($table, $column = NULL) {
     $info = $this->getPrefixInfo($table);
diff --git a/core/lib/Drupal/Core/Database/Driver/sqlite/Connection.php b/core/lib/Drupal/Core/Database/Driver/sqlite/Connection.php
index b970dcf..fbe6ce7 100644
--- a/core/lib/Drupal/Core/Database/Driver/sqlite/Connection.php
+++ b/core/lib/Drupal/Core/Database/Driver/sqlite/Connection.php
@@ -16,8 +16,9 @@
 use Drupal\Core\Database\Connection as DatabaseConnection;
 
 /**
- * Specific SQLite implementation of DatabaseConnection.
- */
+  * SQLite implementation of DatabaseConnection::prepare(). SQLite implementation of
+  * \Drupal\Core\Database\Connection::prepare().
+  */
 class Connection extends DatabaseConnection {
 
   /**
@@ -172,11 +173,11 @@ public function __destruct() {
    * @param bool $condition
    *   A condition that will determine what expression is returned.
    * @param mixed $expr1
-   *   Returned if $condition is results to TRUE.
+   *   Value if $condition is TRUE.
    * @param mixed $expr2
    *   (optional) Returned if $condition results to FALSE.
    *
-   * @return null
+   * @return
    */
   public static function sqlFunctionIf($condition, $expr1, $expr2 = NULL) {
     return $condition ? $expr1 : $expr2;
@@ -186,9 +187,9 @@ public static function sqlFunctionIf($condition, $expr1, $expr2 = NULL) {
    * SQLite compatibility implementation for the GREATEST() SQL function.
    *
    * @param ...
-   *   Variadic parameters.
+   *   Variable parameters.
    *
-   * @return mixed|NULL
+   * @return mixed|null
    *   The maximum of the given arguments.
    */
   public static function sqlFunctionGreatest() {
@@ -202,7 +203,7 @@ public static function sqlFunctionGreatest() {
       return max($args);
     }
     else {
-      return NULL;
+      return null;
     }
   }
 
@@ -210,7 +211,7 @@ public static function sqlFunctionGreatest() {
    * SQLite compatibility implementation for the CONCAT() SQL function.
    *
    * @param ...
-   *   Variadic parameters.
+   *   Variable parameters.
    *
    * @return string
    *   Concatenated input arguments.
@@ -242,12 +243,13 @@ public static function sqlFunctionSubstring($string, $from, $length) {
    * @param string $string
    *   The subject for the substring.
    * @param string $delimiter
-   *   A value to use start point for the returned substring occurring after
-   *   $count.
+   *   A start point for the returned substring occurring after $count.
    * @param int $count
-   *   An offset of of $string.
+   *   An offset of $string.
    *
    * @return string
+   *  A substring of the provided string.
+   *
    */
   public static function sqlFunctionSubstringIndex($string, $delimiter, $count) {
     // If string is empty, simply return an empty string.