# HG changeset patch
# User Adam Chlipala <adam@chlipala.net>
# Date 1403720398 14400
# Node ID 884673e5f7d5e4ee5538e53ef43c07db008e260f
# Parent  d11a7a9c4a738bd936156d6626a17556014cf638
Finish example

diff -r d11a7a9c4a73 -r 884673e5f7d5 tests/tags.ur
--- a/tests/tags.ur	Wed Jun 25 14:04:13 2014 -0400
+++ b/tests/tags.ur	Wed Jun 25 14:19:58 2014 -0400
@@ -11,7 +11,10 @@
         Present => (SELECT I.Id AS Id
                     FROM ({{q}}) AS I
                       JOIN tags ON tags.Id = I.Id AND tags.Tag = {[c.Tag]})
-      | Absent => q
+      | Absent => (SELECT I.Id AS Id
+                   FROM ({{q}}) AS I
+                     LEFT JOIN tags ON tags.Id = I.Id AND tags.Tag = {[c.Tag]}
+                   WHERE tags.Tag IS NULL)
 
 fun withConditions (cs : list condition) : tag_query =
     List.foldl addCondition (SELECT images.Id AS Id FROM images) cs