Question

我写了这个代码,它的工作原理, 但我仍然在想,是否有任何其他解决方案更好,更简单。

$sql = "select * from db_member where username =  $name ";
$result = mysql_query($sql) or error(mysql_error());
if(mysql_num_rows($result) < 1) 
{
error("There is no user with name  $name .");
}

Answer 1

一个更快的方法来做到这一点:

$result = mysql_query("SELECT COUNT(1) FROM db_member WHERE username= ".mysql_real_escape_string($name)." ") or die(mysql_error());
if (mysql_result($result, 0) == 0) {
    echo  There is no user with name   . htmlspecialchars($name, ENT_QUOTES,  UTF-8 ) .  . ;
}

请检查 < a href=> "http://php.net/pdo" rel="nofollow" >http://php.net/pdo , 以更好地处理错误和查询参数....

我想这样用我的口吻... 已经不行了...

Answer 2

不,如果没有其他细节,这是一个很好的解决办法。然而,你可以看一下以下各点:

take care of your indexes. If you could use a where clause on some indexed columns it would be perfect
if you plan to check the existence of an element before insertion, i ld rather catch the error than checking like you re doing.
you could indeed reduce overhead reducing the selection range, like mentionned by another member

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