update db default Exec method

db/db.go

@@ -390,3 +390,13 @@ func Row(dest interface{}, query string, args interface{}) (err error) {
 	err = nstmt.Get(dest, args)
 	return
 }
+
+func Exec(query string, args ...interface{}) (LastInsertId, RowsAffected int64, err error) {
+	defaultDB.conn, err = connect()
+	if err != nil {
+		return
+	}
+
+	LastInsertId, RowsAffected, err = defaultDB.conn.Exec(query, args...)
+	return
+}