javascript - 执行 'COUNT(id)' 查询后，无法从 RowDataPacket 访问 'SELECT COUNT'

Question

我想访问包含实际计数元素数的变量，但我不知道如何访问。

    sql = "SELECT COUNT(id) FROM users WHERE username='" + req.body.username + "' AND password='" + req.body.password + "';";
    con.query(sql, function (err, result) {
    if (err) throw err;
    })

结果是:[ RowDataPacket { 'COUNT(id)': 0 } ] ;我无法使用语法 result.COUNT(id) 访问数据，因为我收到错误:ReferenceError: id is not defined

Answer 1

为 count 使用别名，为了更好的抽象，在查询中使用模板文字

 sql = `SELECT COUNT(id) as count FROM users WHERE username=${req.body.username}  AND password=${req.body.password}`;
    con.query(sql, function (err, result) {
        if (err) throw err;
    })

And For [ RowDataPacket { 'total': 0 } ] ,try this

     sql = `SELECT COUNT(id) as count FROM users WHERE username=${req.body.username}  AND password=${req.body.password}`;
            con.query(sql, function (err, result) {
                if (err) throw err;
                  else{
let results=JSON.parse(JSON.stringify(result)) // gives you an js object array
    } })