Handle unescaped ? when calling toString() on query (#6)

* Fixed unescaped ? and added a test

* Tweaked test to confirm update occurs

* Changed split / join with regex replace

__tests__/index.spec.js

@@ -109,5 +109,18 @@ describe('onDuplicateUpdate', () => {
         email: 'updated-email',
       }));
     });
+
+    it('should correctly escape field with ? character', async () => {
+      await db
+        .insert({ id: 7, name: 'other value' })
+        .into('persons');
+      await db
+        .insert({ id: 7, name: '?' })
+        .into('persons')
+        .onDuplicateUpdate('name');
+      const person = await getById(7);
+
+      expect(person.name).toBe('?');
+    });
   });
 });

lib/index.js

@@ -25,9 +25,9 @@ module.exports.attachOnDuplicateUpdate = function attachOnDuplicateUpdate() {
 
       return result;
     }, { placeholders: [], bindings: [] });
-
+    const escapeKnexString = input => input.replace(/\?/g, '\\?');
     return this.client.raw(
-      `${this.toString()} on duplicate key update ${placeholders.join(', ')}`,
+      `${escapeKnexString(this.toString())} on duplicate key update ${placeholders.join(', ')}`,
       bindings
     );
   };