Fix for sub queries that use UNION

Author: mlilius

src/sqlParser.jison

@@ -197,6 +197,11 @@ main
   | unionClause semicolonOpt EOF { return {nodeType: 'Main', value: $1, hasSemicolon: $2}; }
   ;
 
+selectUnionClause
+  : selectClause { $$ = {type: 'SelectUnion', value: $1}; }
+  | unionClause { $$ = {type: 'SelectUnion', value: $1}; }
+  ;
+
 semicolonOpt
   : ';' { $$ = true }
   | { $$ = false }
@@ -673,6 +678,6 @@ index_hint
   ;
 table_factor
   : identifier partitionOpt aliasOpt index_hint_list_opt { $$ = { type: 'TableFactor', value: $1, partition: $2, alias: $3.alias, hasAs: $3.hasAs, indexHintOpt: $4 } }
-  | '(' selectClause ')' aliasOpt { $$ = { type: 'TableFactor', value: { type: 'SubQuery', value: $2 }, alias: $4.alias, hasAs: $4.hasAs} }
+  | '(' selectUnionClause ')' aliasOpt { $$ = { type: 'TableFactor', value: { type: 'SubQuery', value: $2 }, alias: $4.alias, hasAs: $4.hasAs} }
   | '(' table_references ')' { $$ = $2; $$.hasParentheses = true }
   ;

src/stringify.js

@@ -14,16 +14,16 @@ if (!sqlParser) {
 
   Sql.prototype.travel = function(ast) {
     if (!ast) return;
-  
+
     if (typeof ast === 'string') {
       return this.append(ast);
     }
-  
+
     var processor = this['travel' + ast.type];
     try {
       processor.call(this, ast);
     } catch (error) {
-      throw new Error(error)
+      throw new Error(`Error when trying to process travel${ast.type}:`, error)
     }
   };
 
@@ -292,6 +292,9 @@ if (!sqlParser) {
     this.travel(ast.value);
     this.append(')', true);
   };
+  Sql.prototype.travelSelectUnion = function(ast) {
+    this.travel(ast.value);
+  };
   Sql.prototype.travelIdentifierExpr = function(ast) {
     this.append('{');
     this.travel(ast.identifier);

test/main.test.js

@@ -419,4 +419,22 @@ describe('select grammar support', function() {
   it('bugfix table alias2', function() {
     testParser('select a.* from a t1 join b t2 on t1.a = t2.a')
   })
+
+  it('UNION ALL sub query', function() {
+    testParser(`
+    SELECT
+    col
+    FROM(
+      SELECT
+      col
+      FROM tableA
+  
+      UNION ALL
+  
+      SELECT
+      col
+      FROM tableB
+    )
+    `)
+  })
 });