diff --git a/js/settings.js b/js/settings.js
index da1f8b7..18a3d4d 100644
--- a/js/settings.js
+++ b/js/settings.js
@@ -119,7 +119,7 @@ user_sql.adminSettingsUI = function () {
         );
 
         autocomplete(
-            "#db-table-user-column-uid, #db-table-user-column-email, #db-table-user-column-quota, #db-table-user-column-home, #db-table-user-column-password, #db-table-user-column-name, #db-table-user-column-active, #db-table-user-column-disabled, #db-table-user-column-avatar, #db-table-user-column-salt",
+            "#db-table-user-column-uid, #db-table-user-column-username, #db-table-user-column-email, #db-table-user-column-quota, #db-table-user-column-home, #db-table-user-column-password, #db-table-user-column-name, #db-table-user-column-active, #db-table-user-column-disabled, #db-table-user-column-avatar, #db-table-user-column-salt",
             "/apps/user_sql/settings/autocomplete/table/user"
         );
 
diff --git a/lib/Backend/UserBackend.php b/lib/Backend/UserBackend.php
index 22dc213..6656fdb 100644
--- a/lib/Backend/UserBackend.php
+++ b/lib/Backend/UserBackend.php
@@ -301,15 +301,15 @@ final class UserBackend extends ABackend implements
      * Check if the user's password is correct then return its ID or
      * FALSE on failure.
      *
-     * @param string $uid      The user ID.
+     * @param string $username      The user ID.
      * @param string $password The password.
      *
      * @return string|bool The user ID on success, false otherwise.
      */
-    public function checkPassword(string $uid, string $password)
+    public function checkPassword(string $username, string $password)
     {
         $this->logger->debug(
-            "Entering checkPassword($uid, *)", ["app" => $this->appName]
+            "Entering checkPassword($username, *)", ["app" => $this->appName]
         );
 
         $passwordAlgorithm = $this->getPasswordAlgorithm();
@@ -318,8 +318,8 @@ final class UserBackend extends ABackend implements
         }
 
         $caseSensitive = empty($this->properties[Opt::CASE_INSENSITIVE_USERNAME]);
-        $user = $this->userRepository->findByUid($uid, $caseSensitive);
-        if (!($user instanceof User) || ($caseSensitive && $user->uid !== $uid)) {
+        $user = $this->userRepository->findByUsername($username, $caseSensitive);
+        if (!($user instanceof User) || ($caseSensitive && $user->username !== $username)) {
             return false;
         }
 
diff --git a/lib/Constant/DB.php b/lib/Constant/DB.php
index 0442b13..e7f751d 100644
--- a/lib/Constant/DB.php
+++ b/lib/Constant/DB.php
@@ -55,4 +55,5 @@ final class DB
     const USER_QUOTA_COLUMN = "db.table.user.column.quota";
     const USER_SALT_COLUMN = "db.table.user.column.salt";
     const USER_UID_COLUMN = "db.table.user.column.uid";
+    const USER_USERNAME_COLUMN = "db.table.user.column.username";
 }
diff --git a/lib/Constant/Query.php b/lib/Constant/Query.php
index 8cbff2c..cad6ba9 100644
--- a/lib/Constant/Query.php
+++ b/lib/Constant/Query.php
@@ -36,6 +36,8 @@ final class Query
     const FIND_GROUPS = "find_groups";
     const FIND_USER = "find_user";
     const FIND_USER_CASE_INSENSITIVE = "find_user_case_insensitive";
+    const FIND_USER_BY_USERNAME = "find_user_by_username";
+    const FIND_USER_BY_USERNAME_CASE_INSENSITIVE = "find_user_by_username_case_insensitive";
     const FIND_USER_GROUPS = "find_user_groups";
     const FIND_USERS = "find_users";
     const UPDATE_DISPLAY_NAME = "update_display_name";
@@ -50,4 +52,5 @@ final class Query
     const QUOTA_PARAM = "quota";
     const SEARCH_PARAM = "search";
     const UID_PARAM = "uid";
+    const USERNAME_PARAM = "username";
 }
diff --git a/lib/Model/User.php b/lib/Model/User.php
index 40ebf1c..0349f67 100644
--- a/lib/Model/User.php
+++ b/lib/Model/User.php
@@ -29,9 +29,13 @@ namespace OCA\UserSQL\Model;
 class User
 {
     /**
-     * @var string The UID (username).
+     * @var string The UID (uid).
      */
     public $uid;
+     /**
+     * @var string The user's username for login.
+     */
+    public $username;
     /**
      * @var string The user's email address.
      */
diff --git a/lib/Query/QueryProvider.php b/lib/Query/QueryProvider.php
index 81ff994..8e16148 100644
--- a/lib/Query/QueryProvider.php
+++ b/lib/Query/QueryProvider.php
@@ -76,6 +76,7 @@ class QueryProvider implements \ArrayAccess
         $uQuota = $this->properties[DB::USER_QUOTA_COLUMN];
         $uSalt = $this->properties[DB::USER_SALT_COLUMN];
         $uUID = $this->properties[DB::USER_UID_COLUMN];
+        $uUsername = $this->properties[DB::USER_USERNAME_COLUMN];
 
         $ugGID = $this->properties[DB::USER_GROUP_GID_COLUMN];
         $ugUID = $this->properties[DB::USER_GROUP_UID_COLUMN];
@@ -87,6 +88,7 @@ class QueryProvider implements \ArrayAccess
         $quotaParam = Query::QUOTA_PARAM;
         $searchParam = Query::SEARCH_PARAM;
         $uidParam = Query::UID_PARAM;
+        $usernameParam = Query::USERNAME_PARAM;
 
         $reverseActiveOpt = $this->properties[Opt::REVERSE_ACTIVE];
 
@@ -95,7 +97,7 @@ class QueryProvider implements \ArrayAccess
             (empty($gName) ? "g." . $gGID : "g." . $gName) . " AS name, " .
             (empty($gAdmin) ? "false" : "g." . $gAdmin) . " AS admin";
         $userColumns
-            = "u.$uUID AS uid, " .
+            = "u.$uUID AS uid, u.$uUsername AS username, " .
             (empty($uName) ? "u." . $uUID : "u." . $uName) . " AS name, " .
             (empty($uEmail) ? "null" : "u." . $uEmail) . " AS email, " .
             (empty($uQuota) ? "null" : "u." . $uQuota) . " AS quota, " .
@@ -156,6 +158,18 @@ class QueryProvider implements \ArrayAccess
                 "FROM $user u " .
                 "WHERE lower(u.$uUID) = lower(:$uidParam) " .
                 (empty($uDisabled) ? "" : "AND NOT u.$uDisabled"),
+                
+            Query::FIND_USER_BY_USERNAME =>
+                "SELECT $userColumns, u.$uPassword AS password " .
+                "FROM $user u " .
+                "WHERE u.$uUsername = :$usernameParam " .
+                (empty($uDisabled) ? "" : "AND NOT u.$uDisabled"),
+
+            Query::FIND_USER_BY_USERNAME_CASE_INSENSITIVE =>
+                "SELECT $userColumns, u.$uPassword AS password " .
+                "FROM $user u " .
+                "WHERE lower(u.$uUsername) = lower(:$usernameParam) " .
+                (empty($uDisabled) ? "" : "AND NOT u.$uDisabled"),
 
             Query::FIND_USER_GROUPS =>
                 "SELECT $groupColumns " .
diff --git a/lib/Repository/UserRepository.php b/lib/Repository/UserRepository.php
index 9841cf0..2f2eeec 100644
--- a/lib/Repository/UserRepository.php
+++ b/lib/Repository/UserRepository.php
@@ -74,6 +74,29 @@ class UserRepository
             );
         }
     }
+    
+    /**
+     * Get an user entity object.
+     *
+     * @param string $username           The username.
+     * @param bool   $caseSensitive TRUE for case sensitive search,
+     *                              FALSE for case insensitive search.
+     *
+     * @return User The user entity, NULL if it does not exists or
+     *              FALSE on failure.
+     */
+    public function findByUsername($username, $caseSensitive = true)
+    {
+        if ($caseSensitive) {
+            return $this->dataQuery->queryEntity(
+                Query::FIND_USER_BY_USERNAME, User::class, [Query::USERNAME_PARAM => $username]
+            );
+        } else {
+            return $this->dataQuery->queryEntity(
+                Query::FIND_USER_BY_USERNAME_CASE_INSENSITIVE, User::class, [Query::USERNAME_PARAM => $username]
+            );
+        }
+    }
 
     /**
      * Get an array of user entity objects.