Fixed #29350 -- Fix get_primary_key_column() method in sqlite3 backend

Thanks Tim Graham and Mariusz Felisiak for the reviews.

django/db/backends/sqlite3/introspection.py

@@ -192,9 +192,9 @@ class DatabaseIntrospection(BaseDatabaseIntrospection):
         fields_sql = create_sql[create_sql.index('(') + 1:create_sql.rindex(')')]
         for field_desc in fields_sql.split(','):
             field_desc = field_desc.strip()
-            m = re.search('"(.*)".*PRIMARY KEY( AUTOINCREMENT)?', field_desc)
+            m = re.match('(?:(?:["`\[])(.*)(?:["`\]])|(\w+)).*PRIMARY KEY.*', field_desc)
             if m:
-                return m.groups()[0]
+                return m.group(1) if m.group(1) else m.group(2)
         return None
 
     def _table_info(self, cursor, name):

tests/backends/sqlite/test_introspection.py

+import unittest
+
+from django.db import connection
+from django.test import TestCase
+
+
+@unittest.skipUnless(connection.vendor == 'sqlite', 'SQLite tests')
+class IntrospectionTests(TestCase):
+    def test_get_primary_key_column(self):
+        """
+        Get the primary key column regardless of whether or not it has
+        quotation.
+        """
+        testable_column_strings = (
+            ('id', 'id'), ('[id]', 'id'), ('`id`', 'id'), ('"id"', 'id'),
+            ('[id col]', 'id col'), ('`id col`', 'id col'), ('"id col"', 'id col')
+        )
+        with connection.cursor() as cursor:
+            for column, expected_string in testable_column_strings:
+                sql = 'CREATE TABLE test_primary (%s int PRIMARY KEY NOT NULL)' % column
+                with self.subTest(column=column):
+                    try:
+                        cursor.execute(sql)
+                        field = connection.introspection.get_primary_key_column(cursor, 'test_primary')
+                        self.assertEqual(field, expected_string)
+                    finally:
+                        cursor.execute('DROP TABLE test_primary')