为什么mysql_query()用SELECT语句返回TRUE? [英] Why does mysql_query() return TRUE with a SELECT statement?

问题描述

根据 mysql_query() 的手册以及我所知道的关于此功能的所有知识，我已经使用了很多次，它可以返回资源，如果查询是SELECT，则可以返回FALSE.但是它会不时返回TRUE.

According to the manual of mysql_query() and to everything I know about this function that I used so many times, it can either return a resource or FALSE if the query is a SELECT. Yet it returns TRUE from time to time.

怎么可能?它从来没有发生过.这是PHP 5.3.2中的错误吗?有人知道吗?

How can this be? It never ever happened before. Is this a bug in PHP 5.3.2? Does anyone know anything about this?

代码类似于:

if (!$resource = mysql_query($query, $handle)) {
    throw some exception;
}

var_dump($query);
if ($resource === true && strpos($query, 'SELECT') !== false) {
    throw new Exception('mysql_query() returned TRUE for SELECT');
}

也很难复制.它只会不时发生.我还注意到，这很可能是在服务器突然中断连接的同时发生的，在这种情况下，它应该返回FALSE ...

It's pretty hard to reproduce, too. It happens only from time to time. I also noticed that it's likely this happens at the same time the server interrupts the connection suddenly, in which case it should return FALSE...

推荐答案

如果webbiedave不在正确的轨道上，则在php源中只有一种代码路径可以解决这种情况:

If webbiedave isn't on the right track, there's only one codepath that allows for this situation in the php source:

#if MYSQL_VERSION_ID < 32224
#define PHP_MYSQL_VALID_RESULT(mysql)       \
    (mysql_num_fields(mysql)>0)
#else
#define PHP_MYSQL_VALID_RESULT(mysql)       \
    (mysql_field_count(mysql)>0)
#endif

...

if (!mysql_result) {
    if (PHP_MYSQL_VALID_RESULT(mysql->conn)) { /* query should have returned rows */
        php_error_docref(NULL TSRMLS_CC, E_WARNING, "Unable to save result set");
        RETURN_FALSE;
    } else {
        RETURN_TRUE; // <<< this case
    }
}

我认为这是一个错误.尤其是因为没有真正的方法可以验证这一点-PHP代码中的mysql_num_fields使用的是您没有得到的资源，而不是连接.

I would consider this a bug. Especially since there's no real way to verify this - mysql_num_fields in the PHP code uses the resource that you're not getting, not the connection.

尽管仍然很奇怪，mysql_query的C版本在失去连接时返回零-如果可以，请尝试以下补丁并重新安装mysql扩展:

Although it's still weird that the C version of mysql_query returns zero on lost connection - if you're able to, try the following patch and reinstall the mysql extension:

Index: ext/mysql/php_mysql.c
===================================================================
--- ext/mysql/php_mysql.c       (revision 311719)
+++ ext/mysql/php_mysql.c       (working copy)
@@ -1485,6 +1485,9 @@
                if (PHP_MYSQL_VALID_RESULT(mysql->conn)) { /* query should have returned rows */
                        php_error_docref(NULL TSRMLS_CC, E_WARNING, "Unable to save result set");
                        RETURN_FALSE;
+               } else if( mysql_errno(mysql->conn) != 0 ) {
+                       php_error_docref("http://www.mysql.com/doc" TSRMLS_CC, E_WARNING, "%s", mysql_error(mysql->conn));
+                       RETURN_FALSE;
                } else {
                        RETURN_TRUE;
                }

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