Fixed #30408 -- Fixed crash when adding check constraints with LIKE operator on Oracle and PostgreSQL.

The LIKE operator wildcard generated for contains, startswith, endswith and
their case-insensitive variant lookups was conflicting with parameter
interpolation on CREATE constraint statement execution.

Ideally we'd delegate parameters interpolation in DDL statements on backends
that support it but that would require backward incompatible changes to the
Index and Constraint SQL generating methods.

Thanks David Sanders for the report.

tests/migrations/test_operations.py

@@ -1855,6 +1855,49 @@ class OperationTests(OperationTestBase):
         self.assertEqual(definition[1], [])
         self.assertEqual(definition[2], {'model_name': "Pony", 'constraint': gt_constraint})
 
+    @skipUnlessDBFeature('supports_table_check_constraints')
+    def test_add_constraint_percent_escaping(self):
+        app_label = 'add_constraint_string_quoting'
+        operations = [
+            CreateModel(
+                'Author',
+                fields=[
+                    ('id', models.AutoField(primary_key=True)),
+                    ('name', models.CharField(max_length=100)),
+                    ('rebate', models.CharField(max_length=100)),
+                ],
+            ),
+        ]
+        from_state = self.apply_operations(app_label, ProjectState(), operations)
+        # "%" generated in startswith lookup should be escaped in a way that is
+        # considered a leading wildcard.
+        check = models.Q(name__startswith='Albert')
+        constraint = models.CheckConstraint(check=check, name='name_constraint')
+        operation = migrations.AddConstraint('Author', constraint)
+        to_state = from_state.clone()
+        operation.state_forwards(app_label, to_state)
+        with connection.schema_editor() as editor:
+            operation.database_forwards(app_label, editor, from_state, to_state)
+        Author = to_state.apps.get_model(app_label, 'Author')
+        with self.assertRaises(IntegrityError), transaction.atomic():
+            Author.objects.create(name='Artur')
+        # Literal "%" should be escaped in a way that is not a considered a
+        # wildcard.
+        check = models.Q(rebate__endswith='%')
+        constraint = models.CheckConstraint(check=check, name='rebate_constraint')
+        operation = migrations.AddConstraint('Author', constraint)
+        from_state = to_state
+        to_state = from_state.clone()
+        operation.state_forwards(app_label, to_state)
+        Author = to_state.apps.get_model(app_label, 'Author')
+        with connection.schema_editor() as editor:
+            operation.database_forwards(app_label, editor, from_state, to_state)
+        Author = to_state.apps.get_model(app_label, 'Author')
+        with self.assertRaises(IntegrityError), transaction.atomic():
+            Author.objects.create(name='Albert', rebate='10$')
+        author = Author.objects.create(name='Albert', rebate='10%')
+        self.assertEqual(Author.objects.get(), author)
+
     @skipUnlessDBFeature('supports_table_check_constraints')
     def test_remove_constraint(self):
         project_state = self.set_up_test_model("test_removeconstraint", constraints=[