[tracker] SPARQL: Fix SELECT * with WHERE without variables

[Jürg Billeter <juergbi src gnome org>]

commit fbe2cad701077a16b0795069ea5bdfc86d98e3f1
Author: Jürg Billeter <j bitron ch>
Date:   Wed Nov 24 09:54:16 2010 +0100

    SPARQL: Fix SELECT * with WHERE without variables

 src/libtracker-data/tracker-sparql-pattern.vala |    6 ++++++
 1 files changed, 6 insertions(+), 0 deletions(-)
---
diff --git a/src/libtracker-data/tracker-sparql-pattern.vala b/src/libtracker-data/tracker-sparql-pattern.vala
index 94f6985..a81f57b 100644
--- a/src/libtracker-data/tracker-sparql-pattern.vala
+++ b/src/libtracker-data/tracker-sparql-pattern.vala
@@ -309,6 +309,8 @@ class Tracker.Sparql.Pattern : Object {
 			}
 		} else {
 			for (int i = 0; ; i++) {
+				first = false;
+
 				if (i > 0) {
 					sql.append (", ");
 				}
@@ -338,6 +340,10 @@ class Tracker.Sparql.Pattern : Object {
 			query.bindings.append (binding);
 		}
 
+		if (first) {
+			sql.append ("NULL");
+		}
+
 		// select from results of WHERE clause
 		sql.append (" FROM (");
 		sql.append (pattern_sql.str);