docs: function get(tableName, fieldNames, where, orderBy) {
      if (orderBy && !checkOrderBy(orderBy)) {
        throw new Error('Invalid arg: orderBy');
      }
      if (!db) {
        throw new Error('Not connected');
      }
      let sql = `SELECT ${fieldNames.join(',')} FROM ${tableName}`;
      if (where) {
        sql += ` WHERE ${where}`;
      }
      if (orderBy) {
        sql += ` ORDER BY ${orderBy.join(',')}`;
      }
      return new Promise(((resolve, reject) => {
        db.get(sql, [], (error, row) => {
          if (error) {
            reject(error);
          } else {
            resolve(row);
          }
        });
      }));
    }