MySQL 表锁问题

Question

我认为这可能是一个死锁问题，但我只是在读取表数据。或者一些我看不到的非常简单的东西。

我的$msqli obj 可以访问数据库

但是我对这个错误有点难过.. 我被告知clients 表没有被LOCK TABLES 锁定

欢迎任何建议.. 谢谢 这是我的 PHP 代码

$mysqli = $GLOBALS['mysqli'];
$mysqli->query("LOCK TABLES clients READ, invoices READ, estimates READ");

$mysqli->query("SET @inv='Invoice'");
$mysqli->query("SET @est='Estimate'");

$sql = " (SELECT @inv, name AS client, invoices.id, invoices.ref AS ref, invoices.addTs AS ts \n"
        . "FROM `clients` , `invoices` \n"
        . "WHERE invoices.user_id =  " . $_SESSION['user_id'] . " \n"
        . "AND clients.id = invoices.client_id)\n"
        . "UNION ALL\n"
        . "(SELECT @est, name as client, estimates.id, estimates.ref AS ref, estimates.addTs AS ts \n"
        . "FROM `clients` ,`estimates` \n"
        . "WHERE estimates.user_id =  " . $_SESSION['user_id'] . " \n"
        . "AND clients.id = estimates.client_id) \n"
        . "ORDER BY ts DESC LIMIT 5";

if ($result = $mysqli->query($sql) or die(mysqli_error($mysqli))) {
//Do stuff here
}

当我在 PhpMyAdmin 中运行此 $sql 查询时，它是成功的... 感谢您的帮助..

********************已解决（？）******************

已修复（或似乎已修复）：

引用http://bugs.mysql.com/bug.php?id=6588

“您不能在一个查询中多次使用锁定表 - 为此使用别名。”

所以查询更新为

    $mysqli->query("LOCK TABLES clients_t READ,clients READ ,
                                invoices READ, estimates READ");
$mysqli->query("SET @inv='Invoice'");
$mysqli->query("SET @est='Estimate'");

$sql = " " .
        "(SELECT @inv, name AS client, invoices.id, 
                  invoices.ref AS ref, invoices.addTs AS ts "

        . "FROM `clients` AS clients_t , `invoices`\n"
        . "WHERE invoices.user_id =  " . $_SESSION['user_id'] . " \n"
        . "AND clients_t.id = invoices.client_id)\n"
        . "UNION ALL \n"
        . "(SELECT @est , name AS client, estimates.id, 
                   estimates.ref AS ref, estimates.addTs AS ts\n"
        . "FROM `clients` ,`estimates` \n"
        . "WHERE estimates.user_id =  " . $_SESSION['user_id'] . "  \n"
        . "AND clients.id = estimates.client_id)\n"
        . "ORDER BY ts DESC LIMIT 5";

我还需要锁定别名表clients_t。 无论如何，对于未来的用户，我希望这会有所帮助。

Answer 1

有点挑剔，但明智的做法是对 $_SESSION['user_id'] 输入执行诸如添加斜杠或 mysql_real_escape_string 之类的操作以避免注入问题。