diff --git a/src/executor/select.rs b/src/executor/select.rs
index 32f633f8..afd300d5 100644
--- a/src/executor/select.rs
+++ b/src/executor/select.rs
@@ -1054,6 +1054,10 @@ where
                 } else {
                     acc.insert(key, vec![value]);
                 }
+            } else {
+                if acc.get(&key).is_none() {
+                    acc.insert(key, vec![]);
+                }
             }
 
             acc