Add transaction utility functions to DB interface

lib/www/server/lib/db/connection.js

@@ -14,6 +14,21 @@ numericTypeOIDs.forEach(oid => {
 // 	types.setTypeParser(oid, function (v) { return JSON.parse(v); });
 // })
 
-module.exports = {
+const transaction = {
-	pool
+	async begin (client) {
+		return await client.query("BEGIN;");
+	},
+
+	async commit (client) {
+		return await client.query("COMMIT;");
+	},
+
+	async rollback (client) {
+		return await client.query("ROLLBACK;");
+	}
+};
+
+module.exports = {
+	pool,
+	transaction,
 };