MySQL表锁问题

Question

我认为这可能是一个死锁问题，但我只读取表数据。或者一些我看不见的很简单的东西。

我的$msqli obj可以用于db访问。

但我对这个错误有点困惑..。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$sql中运行这个PhpMyAdmin查询时，它是成功的.谢谢你的帮助..。

********************SOLVED (?) ******************

固定(或似乎是)：

来自http://bugs.mysql.com/bug.php?id=6588的报价

“不能在一个查询中多次使用锁定的表--为此使用别名。”

因此，查询被更新为

    $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

虽然有点挑剔，但明智的做法是对$_SESSION‘’user_id‘输入进行加号或mysql_real_escape_string，以避免注入问题。