mySQL/PHP: SQL语句、查询和结果赋值在一行？

Question

有没有可能只用一行(或者更短)重写下面的代码，甚至可以用一条if (result > 0)语句？

// a simple query that ALWAYS gets ONE table row as result
$query  = $this->db->query("SELECT id FROM mytable WHERE this = that;");
$result = $query->fetch_object();
$id     = $result->id;

我见过像三元运算符(here和here - btw )这样的极好的、极少的构造，将4-5行放在一起，所以可能有一些东西可以用于像上面这样的单结果SQL查询。

Answer 1

你可以缩短

$query  = $this->db->query("SELECT id FROM mytable WHERE this = that;");
$result = $query->fetch_object();
$id     = $result->id;

至

$id = $this->db->query("SELECT id FROM mytable WHERE this = that")->fetch_object()->id;

但是，如果任何函数返回意外的响应，则原始代码将发出错误。最好这样写：

$query  = $this->db->query("SELECT id FROM mytable WHERE this = that");
if (!$query) {
     error_log('query() failed');
     return false;
}
$result = $query->fetch_object();
if (!$result) {
     error_log('fetch_object() failed');
     return false;
}
$id     = $result->id;