diff options
| -rw-r--r-- | lib/gitlab/sql/union.rb | 6 | ||||
| -rw-r--r-- | spec/lib/gitlab/sql/union_spec.rb | 7 |
2 files changed, 12 insertions, 1 deletions
diff --git a/lib/gitlab/sql/union.rb b/lib/gitlab/sql/union.rb index f30c771837a..c99b262f1ca 100644 --- a/lib/gitlab/sql/union.rb +++ b/lib/gitlab/sql/union.rb @@ -26,7 +26,11 @@ module Gitlab @relations.map { |rel| rel.reorder(nil).to_sql }.reject(&:blank?) end - fragments.join("\n#{union_keyword}\n") + if fragments.any? + fragments.join("\n#{union_keyword}\n") + else + 'NULL' + end end def union_keyword diff --git a/spec/lib/gitlab/sql/union_spec.rb b/spec/lib/gitlab/sql/union_spec.rb index 8026fba9f0a..fe6422c32b6 100644 --- a/spec/lib/gitlab/sql/union_spec.rb +++ b/spec/lib/gitlab/sql/union_spec.rb @@ -29,5 +29,12 @@ describe Gitlab::SQL::Union do expect(union.to_sql).to include('UNION ALL') end + + it 'returns `NULL` if all relations are empty' do + empty_relation = User.none + union = described_class.new([empty_relation, empty_relation]) + + expect(union.to_sql).to eq('NULL') + end end end |