为何我的pool.query返回"undefined"？数据库查询解构问题咨询

第一个查询可正常返回rows：

(async () => {
  const {rows} = await pool.query('SELECT * FROM accounts');
  console.log(rows);
})();

但以下查询返回undefined：

(async () => {
  const {user} = await pool.query(`SELECT * FROM accounts WHERE username = '${req.body.username}'`);
  console.log(user);
})();

已知req.body.username参数正确，该查询理应返回1行数据。如果去掉user外层的解构语法{}，改用const user而非const {user}，就能得到包含字段定义的完整返回结果：

(async () => {
  const user = await pool.query(`SELECT * FROM accounts WHERE username = '${req.body.username}'`);
  console.log(user);
})();

内容的提问来源于stack exchange，提问作者Paul