大神帮帮我优化一下下面的代码，我感觉我用这段mysql特别影响速度

Question

public function getOneNav(){
$_sql = "SELECT
n1.id,
n1.nav_name,
n1.nav_info,
n2.id iid,
n2.nav_name nnav_name
FROM
cms_nav n1
LEFT JOIN
cms_nav n2
ON
n1.pid = n2.id
WHERE
n1.id='$this->id'
OR
n1.nav_name='$this->nav_name'
LIMIT
1";
return parent::one($_sql);
}

Answer 1

查询条件添加索引了没