diff --git a/codeGrader/backend/db/ExecutionResult.py b/codeGrader/backend/db/ExecutionResult.py
index 0b036de..455763b 100644
--- a/codeGrader/backend/db/ExecutionResult.py
+++ b/codeGrader/backend/db/ExecutionResult.py
@@ -74,7 +74,7 @@ class ExecutionResult(Base):
 
     testcase_id = Column(
         Integer,
-        ForeignKey(TestCase.id, onupdate="CASCADE"),
+        ForeignKey(TestCase.id, ondelete="SET NULL", onupdate="CASCADE"),
         nullable=True,
         index=True
     )