add alias only for union blocks

Author: RoobinGood

lib/dialects/base/blocks.js

@@ -368,17 +368,25 @@ module.exports = function(dialect) {
 	});
 
 	dialect.blocks.add('query', function(params) {
-		return dialect.buildTemplate('subQuery', {
-			queryBody: params.query,
-			alias: params.query.alias
-		});
+		var templateParams = {
+			queryBody: params.query
+		};
+		if (params.query && params.query.type === 'union') {
+			templateParams.alias = params.query.alias;
+		}
+
+		return dialect.buildTemplate('subQuery', templateParams);
 	});
 
 	dialect.blocks.add('select', function(params) {
-		return dialect.buildTemplate('subQuery', {
-			queryBody: params.select,
-			alias: params.select.alias
-		});
+		var templateParams = {
+			queryBody: params.select
+		};
+		if (params.select && params.select.type === 'union') {
+			templateParams.alias = params.select.alias;
+		}
+
+		return dialect.buildTemplate('subQuery', templateParams);
 	});
 
 	dialect.blocks.add('queries', function(params) {