diff --git a/django/db/backends/mysql/introspection.py b/django/db/backends/mysql/introspection.py
index f40e8962f8..0a22357cf9 100644
--- a/django/db/backends/mysql/introspection.py
+++ b/django/db/backends/mysql/introspection.py
@@ -1,4 +1,3 @@
-import re
 from collections import namedtuple
 
 from MySQLdb.constants import FIELD_TYPE
@@ -11,7 +10,6 @@ from django.utils.encoding import force_text
 
 FieldInfo = namedtuple('FieldInfo', FieldInfo._fields + ('extra', 'default'))
 InfoLine = namedtuple('InfoLine', 'col_name data_type max_len num_prec num_scale extra column_default')
-foreign_key_re = re.compile(r"\sCONSTRAINT `[^`]*` FOREIGN KEY \(`([^`]*)`\) REFERENCES `([^`]*)` \(`([^`]*)`\)")
 
 
 class DatabaseIntrospection(BaseDatabaseIntrospection):
diff --git a/django/db/backends/oracle/introspection.py b/django/db/backends/oracle/introspection.py
index c058418ec3..6048c878d8 100644
--- a/django/db/backends/oracle/introspection.py
+++ b/django/db/backends/oracle/introspection.py
@@ -1,5 +1,3 @@
-import re
-
 import cx_Oracle
 
 from django.db.backends.base.introspection import (
@@ -7,8 +5,6 @@ from django.db.backends.base.introspection import (
 )
 from django.utils.encoding import force_text
 
-foreign_key_re = re.compile(r"\sCONSTRAINT `[^`]*` FOREIGN KEY \(`([^`]*)`\) REFERENCES `([^`]*)` \(`([^`]*)`\)")
-
 
 class DatabaseIntrospection(BaseDatabaseIntrospection):
     # Maps type objects to Django Field types.