Node.js布尔变量不改变值

I have following code:

我有以下代码：

app.post('/', function (req, res)
    {
        /*
        connection is created with mysql
         */
        var success = true
        connection.query(sql, [values], function (err, result)
        {
            success = false
        })
        connection.end()
        console.log(success)
    }
)
app.post('/'