further cleanup of normalization

Author: dimitri-yatsenko

book/30-schema-design/055-normalization.ipynb

@@ -123,7 +123,7 @@
         "```\n",
         "Enrollment table with composite key (student_id, course_id)\n",
         "┌────────────┬───────────┬──────────────┬──────────────┬───────────────┐\n",
-        "│*student_id │*course_id │ student_name │ student_email│ course_title  │\n",
+        "│student_id* │course_id* │ student_name │ student_email│ course_title  │\n",
         "├────────────┼───────────┼──────────────┼──────────────┼───────────────┤\n",
         "│ 1          │ CS101     │ Alice        │ [email protected]    │ Databases     │\n",
         "│ 1          │ CS102     │ Alice        │ [email protected]    │ Algorithms    │ ← Redundant!\n",
@@ -143,7 +143,7 @@
         "```\n",
         "Student table:                Course table:              Enrollment table:\n",
         "┌────────────┬──────┬───────┐ ┌───────────┬──────────┐ ┌────────────┬───────────┐\n",
-        "│*student_id │ name │ email │ │*course_id │ title    │ │*student_id │*course_id │\n",
+        "│student_id* │ name │ email │ │course_id* │ title    │ │ student_id*│ course_id*│\n",
         "├────────────┼──────┼───────┤ ├───────────┼──────────┤ ├────────────┼───────────┤\n",
         "│ 1          │ Alice│ a@edu │ │ CS101     │ Databases│ │ 1          │ CS101     │\n",
         "│ 2          │ Bob  │ b@edu │ │ CS102     │ Algos    │ │ 1          │ CS102     │\n",
@@ -191,7 +191,7 @@
         "```\n",
         "Student table:                    Department table:\n",
         "┌────────────┬──────┬────────┐   ┌─────────────┬─────────┬──────────┐\n",
-        "│*student_id │ name │ dept   │   │*dept_code   │ name    │ building │\n",
+        "│student_id* │ name │ dept   │   │ dept_code*  │ name    │ building │\n",
         "├────────────┼──────┼────────┤   ├─────────────┼─────────┼──────────┤\n",
         "│ 1          │ Alice│ CS     │   │ CS          │ Comp Sci│ Bldg A   │\n",
         "│ 2          │ Bob  │ CS     │   │ MATH        │ Math    │ Bldg B   │\n",
@@ -593,8 +593,8 @@
         "# The relationship is semantically broken, even though FK constraint is satisfied\n",
         "\n",
         "# DELETE makes this explicit:\n",
-        "(Mouse & {'mouse_id': 1}).delete()  # ERROR: Experiment references this mouse!\n",
-        "# Forces you to delete and repopulate the dependent data\n",
+        "(Mouse & {'mouse_id': 1}).delete()  # Experiment references this mouse!\n",
+        "# Cascades the delete to Experiment forces you to repopulate the dependent data\n",
         "```"
       ]
     },