diff --git a/src/entities/attribute.js b/src/entities/attribute.js
new file mode 100644
index 000000000..2cecc29dd
--- /dev/null
+++ b/src/entities/attribute.js
@@ -0,0 +1,11 @@
+"use strict";
+
+const Entity = require('./entity');
+
+class Attribute extends Entity {
+    async getNote() {
+        return this.sql.getEntity("SELECT * FROM notes WHERE noteId = ?", [this.noteId]);
+    }
+}
+
+module.exports = Attribute;
\ No newline at end of file
diff --git a/src/entities/entity.js b/src/entities/entity.js
new file mode 100644
index 000000000..0228fab42
--- /dev/null
+++ b/src/entities/entity.js
@@ -0,0 +1,13 @@
+"use strict";
+
+class Entity {
+    constructor(sql, row) {
+        this.sql = sql;
+
+        for (const key in row) {
+            this[key] = row[key];
+        }
+    }
+}
+
+module.exports = Entity;
\ No newline at end of file
diff --git a/src/entities/note.js b/src/entities/note.js
index 367ef4ce1..9e255df1a 100644
--- a/src/entities/note.js
+++ b/src/entities/note.js
@@ -1,20 +1,22 @@
 "use strict";
 
-class Note {
-    constructor(sql, row) {
-        this.sql = sql;
+const Entity = require('./entity');
 
-        for (const key in row) {
-            this[key] = row[key];
-        }
+class Note extends Entity {
+    async getAttributes() {
+        return this.sql.getEntities("SELECT * FROM attributes WHERE noteId = ?", [this.noteId]);
     }
 
-    async attributes() {
-        return this.sql.getRows("SELECT * FROM attributes WHERE noteId = ?", [this.noteId]);
+    async getAttribute(name) {
+        return this.sql.getEntity("SELECT * FROM attributes WHERE noteId = ? AND name = ?", [this.noteId, name]);
     }
 
-    async revisions() {
-        return this.sql.getRows("SELECT * FROM note_revisions WHERE noteId = ?", [this.noteId]);
+    async getRevisions() {
+        return this.sql.getEntities("SELECT * FROM note_revisions WHERE noteId = ?", [this.noteId]);
+    }
+
+    async getTrees() {
+        return this.sql.getEntities("SELECT * FROM note_tree WHERE isDeleted = 0 AND noteId = ?", [this.noteId]);
     }
 }
 
diff --git a/src/entities/note_revision.js b/src/entities/note_revision.js
new file mode 100644
index 000000000..17419b6e1
--- /dev/null
+++ b/src/entities/note_revision.js
@@ -0,0 +1,11 @@
+"use strict";
+
+const Entity = require('./entity');
+
+class NoteRevision extends Entity {
+    async getNote() {
+        return this.sql.getEntity("SELECT * FROM notes WHERE noteId = ?", [this.noteId]);
+    }
+}
+
+module.exports = NoteRevision;
\ No newline at end of file
diff --git a/src/entities/note_tree.js b/src/entities/note_tree.js
new file mode 100644
index 000000000..391c4780b
--- /dev/null
+++ b/src/entities/note_tree.js
@@ -0,0 +1,15 @@
+"use strict";
+
+const Entity = require('./entity');
+
+class NoteTree extends Entity {
+    async getNote() {
+        return this.sql.getEntity("SELECT * FROM note_tree WHERE isDeleted = 0 AND noteId = ?", [this.noteId]);
+    }
+
+    async getParentNote() {
+        return this.sql.getEntity("SELECT * FROM note_tree WHERE isDeleted = 0 AND parentNoteId = ?", [this.parentNoteId]);
+    }
+}
+
+module.exports = NoteTree;
\ No newline at end of file
diff --git a/src/services/sql.js b/src/services/sql.js
index 82dedba64..cbbd732d4 100644
--- a/src/services/sql.js
+++ b/src/services/sql.js
@@ -7,6 +7,9 @@ const sqlite = require('sqlite');
 const app_info = require('./app_info');
 const resource_dir = require('./resource_dir');
 const Note = require('../entities/note');
+const NoteRevision = require('../entities/note_revision');
+const NoteTree = require('../entities/note_tree');
+const Attribute = require('../entities/attribute');
 
 async function createConnection() {
     return await sqlite.open(dataDir.DOCUMENT_PATH, {Promise});
@@ -137,13 +140,40 @@ async function getRows(query, params = []) {
 async function getEntities(query, params = []) {
     const rows = await getRows(query, params);
 
-    return rows.map(row => new Note(module.exports, row));
+    return rows.map(createEntityFromRow);
 }
 
 async function getEntity(query, params = []) {
-    const rows = await getRows(query, params);
+    const row = await getRowOrNull(query, params);
 
-    return rows.map(row => new Note(module.exports, row));
+    if (!row) {
+        return null;
+    }
+
+    return createEntityFromRow(row);
+}
+
+function createEntityFromRow(row) {
+    let entity;
+    let sql = module.exports;
+
+    if (row.attributeId) {
+        entity = new Attribute(sql, row);
+    }
+    else if (row.noteRevisionId) {
+        entity = new NoteRevision(sql, row);
+    }
+    else if (row.noteTreeId) {
+        entity = new NoteTree(sql, row);
+    }
+    else if (row.noteId) {
+        entity = new Note(sql, row);
+    }
+    else {
+        throw new Error('Unknown entity type for row: ' + JSON.stringify(row));
+    }
+
+    return entity;
 }
 
 async function getMap(query, params = []) {