Php 按id号mysql获取记录

这是我的数据库结构

id   userid
1    x
2    xx
3    xxx
4    xx

我想用php显示第3行。仅按行号显示用户ID

结果应该是：

xxx

试试这个

select userid from table where id=3

只需使用这个查询

SELECT userid FROM table WHERE id=3

这应该行得通

<?php
    $connection = new mysqli("localhost", "db_username", "db_password", "db_name");
    $result = mysqli_query($connection, "SELECT * FROM `table_name` WHERE `id` = '3' LIMIT 1");
    $record = mysqli_fetch_object($result);
    echo $record->userid;
?>

看看这里的答案和sqlfiddle:

mysql:

php:

从id=3的表格中选择userid
@user3371310，看看我的答案；
SELECT id, userid 
FROM t 
WHERE id=3;

$result = mysqli_query($connection, "SELECT id,userid FROM t WHERE id = 3");