diff --git a/api/s10_status.py b/api/s10_status.py
index 6088dc0..b99b11e 100644
--- a/api/s10_status.py
+++ b/api/s10_status.py
@@ -52,7 +52,8 @@ def set_status(name: str, cs: ChangeSet) -> ChangeSet:
     new = Status(raw_new)
 
     redo_sql = f"delete from status where link = {new.f_link};"
-    redo_sql += f"\ninsert into status (link, status, setting) values ({new.f_link}, {new.f_status}, {new.f_setting});"
+    if new.status != None or new.setting != None:
+        redo_sql += f"\ninsert into status (link, status, setting) values ({new.f_link}, {new.f_status}, {new.f_setting});"
 
     undo_sql = f"delete from status where link = {old.f_link};"
     if old.status != None or old.setting != None:
diff --git a/api/s11_patterns.py b/api/s11_patterns.py
index dc4d996..40c5bed 100644
--- a/api/s11_patterns.py
+++ b/api/s11_patterns.py
@@ -26,7 +26,8 @@ def set_pattern(name: str, cs: ChangeSet) -> ChangeSet:
     # TODO: transaction ?
     redo_sql = f"delete from patterns where id = {f_id};"
     redo_sql += f"\ndelete from _pattern where id = {f_id};"
-    redo_sql += f"\ninsert into _pattern (id) values ({f_id});"
+    if len(cs.operations[0]['factors']) > 0:
+        redo_sql += f"\ninsert into _pattern (id) values ({f_id});"
     for factor in cs.operations[0]['factors']:
         f_factor = float(factor)
         redo_sql += f"\ninsert into patterns (id, factor) values ({f_id}, {f_factor});"
@@ -34,7 +35,8 @@ def set_pattern(name: str, cs: ChangeSet) -> ChangeSet:
 
     undo_sql = f"delete from patterns where id = {f_id};"
     undo_sql += f"\ndelete from _pattern where id = {f_id};"
-    undo_sql += f"\ninsert into _pattern (id) values ({f_id});"
+    if len(old['factors']) > 0:
+        undo_sql += f"\ninsert into _pattern (id) values ({f_id});"
     for f_factor in old['factors']:
         undo_sql += f"\ninsert into patterns (id, factor) values ({f_id}, {f_factor});"
 
diff --git a/api/s12_curves.py b/api/s12_curves.py
index 42452f7..fa12478 100644
--- a/api/s12_curves.py
+++ b/api/s12_curves.py
@@ -28,7 +28,8 @@ def set_curve(name: str, cs: ChangeSet) -> ChangeSet:
     # TODO: transaction ?
     redo_sql = f"delete from curves where id = {f_id};"
     redo_sql += f"\ndelete from _curve where id = {f_id};"
-    redo_sql += f"\ninsert into _curve (id) values ({f_id});"
+    if len(cs.operations[0]['coords']) > 0:
+        redo_sql += f"\ninsert into _curve (id) values ({f_id});"
     for xy in cs.operations[0]['coords']:
         x, y = float(xy['x']), float(xy['y'])
         f_x, f_y = x, y
@@ -37,7 +38,8 @@ def set_curve(name: str, cs: ChangeSet) -> ChangeSet:
 
     undo_sql = f"delete from curves where id = {f_id};"
     undo_sql += f"\ndelete from _curve where id = {f_id};"
-    undo_sql += f"\ninsert into _curve (id) values ({f_id});"
+    if len(old['coords']) > 0:
+        undo_sql += f"\ninsert into _curve (id) values ({f_id});"
     for xy in old['coords']:
         f_x, f_y = xy['x'], xy['y']
         undo_sql += f"\ninsert into curves (id, x, y) values ({f_id}, {f_x}, {f_y});"