为什么在mysql_query(“string”)中使用$query而不是直接查询字符串？
有人可以向我解释为什么以下内容不起作用：
mysql_query("DELETE FROM `categories` WHERE `id` = '{$id}'");
而以下内容确实有效：
$query = "DELETE FROM `categories` WHERE `id` = '{$id}'";
mysql_query($query);
Could someone please explain to me why the following doesn't work:
mysql_query("DELETE FROM `categories` WHERE `id` = '{$id}'");
Whereas the following does work:
$query = "DELETE FROM `categories` WHERE `id` = '{$id}'";
mysql_query($query);
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它们的工作原理应该完全相同。
试试这个：
这对我总是有效。但有时将其放入变量中可以更轻松地使用。
They both should work exactly the same.
Try this:
That always works for me. But putting it in a variable makes it easier to work with sometimes.
两者没有区别。两者都容易受到 SQL 注入的攻击。您应该使用准备好的语句或
mysql_real_escape_string。There's no difference between the two. Both are vulnerable to SQL injection, as well. You should use prepared statements or
mysql_real_escape_string.两者之间没有功能差异，但将查询存储在单独的变量中可以更轻松地调试生成的语句。
例如
There's no functional different between the two, but storing the query in a separate variable makes it easier to debug the statement that's produced.
e.g.
我怀疑在线示例刚刚开始使用单独的
$query变量，人们在没有真正考虑它的情况下复制了它，然后更多的示例实现了它，现在很多人都这样做，但不一定知道为什么。这就是生活。I suspect online examples just started using a separate
$queryvariable, and people copied it without really thinking about it, and then more examples implemented that, and now tons of people do it without necessarily knowing why. C'est la vie.