added comments

DB.py

@@ -9,6 +9,7 @@ class Database:
     
 
     def _setup_tables(self):
+        # create the shifts table.
         cur = self._con.cursor()
         cur.execute('''
         CREATE TABLE IF NOT EXISTS shifts (
@@ -27,10 +28,12 @@ class Database:
 
 
     def insert_shifts(self, shifts):
+        # start db connection
         cur = self._con.cursor()
         inserted = 0
 
         for shift in shifts:
+            # parse all information from the shift
             start = shift.get('start_datetime', 'N/A')
             end = shift.get('end_datetime', 'N/A')
 
@@ -38,6 +41,7 @@ class Database:
             duration = shift.get('duration', 'N/A')
             description = shift.get('shift_remark', shift.get('description', 'N/A'))
             
+            # insert it into the db.
             cur.execute("""
                 INSERT OR IGNORE INTO shifts 
                 (shift_start, shift_end, department, duration, description)