Index: src/main/resources/db/migration/V1__init_ddl.sql
===================================================================
--- src/main/resources/db/migration/V1__init_ddl.sql	(revision be4e5624790a6a669f74e1fdacc2d9784700a24c)
+++ src/main/resources/db/migration/V1__init_ddl.sql	(revision 489e63703353a8dbbad7bffc0ab1ea825b7c47b4)
@@ -135,8 +135,8 @@
 (
     id serial primary key,
-    blacklisted_from     INT REFERENCES topic_thread (id) ON DELETE CASCADE,
-    refers_to      INT REFERENCES users (id) ON DELETE CASCADE,
-    blacklisted_by INT REFERENCES moderator (id) ON DELETE CASCADE,
-    start_date   TIMESTAMP,
+    blacklisted_from     INT REFERENCES topic_thread (id) ON DELETE CASCADE NOT NULL ,
+    refers_to      INT REFERENCES users (id) ON DELETE CASCADE NOT NULL,
+    blacklisted_by INT REFERENCES moderator (id) ON DELETE CASCADE NOT NULL,
+    start_date   TIMESTAMP NOT NULL,
     end_date     TIMESTAMP,
     reason       TEXT,
@@ -145,6 +145,6 @@
 CREATE TABLE developer_associated_with_project
 (
-    in_project   INT REFERENCES project_thread (id) on delete cascade,
-    about_dev INT REFERENCES developer (id) on delete cascade,
+    in_project   INT REFERENCES project_thread (id) on delete cascade NOT NULL,
+    about_dev INT REFERENCES developer (id) on delete cascade NOT NULL,
     started_at   TIMESTAMP DEFAULT NOW() NOT NULL,
     ended_at     TIMESTAMP,