Add migration.

biscuit/apps/chronos/migrations/0002_make_unique.py

+# Generated by Django 2.2.3 on 2019-07-24 21:26
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('chronos', '0001_initial'),
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name='subject',
+            name='abbrev',
+            field=models.CharField(max_length=10, unique=True, verbose_name='Abbreviation of subject in timetable'),
+        ),
+        migrations.AlterField(
+            model_name='subject',
+            name='name',
+            field=models.CharField(max_length=30, unique=True, verbose_name='Long name of subject'),
+        ),
+        migrations.AlterUniqueTogether(
+            name='timeperiod',
+            unique_together={('weekday', 'period')},
+        ),
+    ]