javascript - 如何在 NodeJS 中访问 SQL 请求的结果？

Question

如何在 JavaScript 中访问 SQL 请求的结果并将其存储在变量中？

SELECT COUNT(*) FROM account where username='Mashiro';

+----------+
| COUNT(*) |
+----------+
|        9 |
+----------+

我的代码:

    con.connect(function(err) {
        if (err)throw err;
            var sql = ("SELECT COUNT(*) FROM account where username=?");
            con.query(sql,[username],function (err, result){
        if (err)throw err;
            console.log(result);

            var x = ???????????

            return result;
        })
    })
}

我想将 x 变量设置为“9”，如下所示:

console.log(x);    >>> 9

Answer 1

使用过滤器选择从表中选择记录时，您可以使用“WHERE”语句过滤选择:

var mysql = require('mysql');

var con = mysql.createConnection({
  host: "localhost",
  user: "yourusername",
  password: "yourpassword",
  database: "mydb"
});

con.connect(function(err) {
  if (err) throw err;
  con.query("SELECT COUNT(*) FROM customers WHERE username = ?", [$username], function (err, result) {
    if (err) throw err;
    console.log(result);
  });
});

更多示例:https://www.w3schools.com/nodejs/nodejs_mysql_where.asp

更多带有准备语句的示例等等:https://evertpot.com/executing-a-mysql-query-in-nodejs/