Handle UNION, UNION ALL and EXCEPT in SELECT queries

Author: Mehmet Emin KARAKAŞ (#136)
pganalyze · Jul 1, 2019 · 823155c · 823155c
1 parent ef5fc6b
commit 823155c
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Showing 2 changed files with 24 additions and 3 deletions.
diff --git a/lib/pg_query/deparse.rb b/lib/pg_query/deparse.rb
@@ -264,7 +264,7 @@ def deparse_columnref(node)
     end
 
     def deparse_a_arrayexp(node)
-      'ARRAY[' + node['elements'].map do |element|
+      'ARRAY[' + (node['elements'] || []).map do |element|
         deparse_item(element)
       end.join(', ') + ']'
     end
@@ -954,6 +954,8 @@ def deparse_when(node)
     def deparse_sublink(node)
       if node['subLinkType'] == SUBLINK_TYPE_ANY
         format('%s IN (%s)', deparse_item(node['testexpr']), deparse_item(node['subselect']))
+      elsif node['subLinkType'] == SUBLINK_TYPE_ALL
+        format('%s %s ALL (%s)', deparse_item(node['testexpr']), deparse_item(node['operName'][0], :operator), deparse_item(node['subselect']))
       elsif node['subLinkType'] == SUBLINK_TYPE_EXISTS
         format('EXISTS(%s)', deparse_item(node['subselect']))
       else
@@ -977,15 +979,22 @@ def deparse_row(node)
     def deparse_select(node) # rubocop:disable Metrics/CyclomaticComplexity
       output = []
 
+      output << deparse_item(node['withClause']) if node['withClause']
+
       if node['op'] == 1
         output << deparse_item(node['larg'])
         output << 'UNION'
         output << 'ALL' if node['all']
         output << deparse_item(node['rarg'])
-        return output.join(' ')
+        output.join(' ')
       end
 
-      output << deparse_item(node['withClause']) if node['withClause']
+      if node['op'] == 3
+        output << deparse_item(node['larg'])
+        output << 'EXCEPT'
+        output << deparse_item(node['rarg'])
+        output.join(' ')
+      end
 
       if node[TARGET_LIST_FIELD]
         output << 'SELECT'

diff --git a/spec/lib/pg_query/deparse_spec.rb b/spec/lib/pg_query/deparse_spec.rb
@@ -74,6 +74,18 @@
         it { is_expected.to eq query }
       end
 
+      context 'UNION or UNION ALL' do
+        let(:query) { 'WITH kodsis AS (SELECT * FROM "application"), kodsis2 AS (SELECT * FROM "application") SELECT * FROM "kodsis" UNION SELECT * FROM "kodsis" ORDER BY "id" DESC' }
+
+        it { is_expected.to eq query }
+      end
+
+      context 'EXCEPT' do
+        let(:query) { "SELECT \"a\" FROM \"kodsis\" EXCEPT SELECT \"a\" FROM \"application\"" }
+
+        it { is_expected.to eq query }
+      end
+
       context 'with specific column alias' do
         let(:query) { "SELECT * FROM (VALUES ('anne', 'smith'), ('bob', 'jones'), ('joe', 'blow')) names(\"first\", \"last\")" }