在删除之前，如何获取多表删除查询在mySQL中影响的行数？

我有一个相当复杂的DELETE查询，我需要将其分解为多个批次，但在执行查询之前，我无法确定要删除多少行。下面是我想要计算的查询：

DELETE parts, binaries FROM parts LEFT JOIN binaries ON binaries.ID = parts.binaryID LEFT JOIN releasenfo rn ON rn.binaryID = binaries.ID WHERE binaries.procstat IN (4, 6) AND (rn.binaryid IS NULL OR (rn.binaryid IS NOT NULL AND rn.nfo IS NOT NULL))) OR binaries.dateadded < '2013-01-04 22:01:17' - INTERVAL 36 HOUR;

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您可以简单地尝试以下方法：

SELECT * FROM parts p 
LEFT JOIN binaries b ON b.ID = p.binaryID AND b.procstat IN (4, 6) 
LEFT JOIN releasenfo rn ON rn.binaryID = b.ID 
WHERE rn.binaryid IS NULL OR (rn.binaryid IS NOT NULL AND rn.nfo IS NOT NULL) OR 
        b.dateadded < '2013-01-04 22:01:17' - INTERVAL 36 HOUR;

DELETE p, b FROM parts p 
LEFT JOIN binaries b ON b.ID = p.binaryID AND b.procstat IN (4, 6) 
LEFT JOIN releasenfo rn ON rn.binaryID = b.ID 
WHERE rn.binaryid IS NULL OR (rn.binaryid IS NOT NULL AND rn.nfo IS NOT NULL) OR 
        b.dateadded < '2013-01-04 22:01:17' - INTERVAL 36 HOUR;

从零件p中选择*
（4，6）中的b.ID=p.binaryID和b.procstat上的左连接二进制文件b
rn.binaryID=b.ID上的左连接releasefo rn
其中rn.binaryid为NULL或（rn.binaryid不为NULL且rn.nfo不为NULL）或
b、 新增日期<'2013-01-04 22:01:17'-间隔36小时；
从零件p中删除零件p、b
（4，6）中的b.ID=p.binaryID和b.procstat上的左连接二进制文件b
rn.binaryID=b.ID上的左连接releasefo rn
其中rn.binaryid为NULL或（rn.binaryid不为NULL且rn.nfo不为NULL）或
b、 新增日期<'2013-01-04 22:01:17'-间隔36小时；

这样做可以节省什么？要计算出受影响的行数，必须执行查询。如果这是可能的，您需要执行两次。您最好将其重构为单个表delete语句。我希望使用一个循环，将查询限制为每次传递10000行，并在执行时向用户输出状态。这对我来说似乎是一个非常糟糕的主意。只需使用查询进程就可以了。比如什么？我添加了示例代码，这样您就可以了解我在尝试做什么。这可能需要数小时才能完全运行。这会导致错误。您的SQL语法有错误；查看与您的MySQL服务器版本相对应的手册，以了解使用near'）或二进制文件的正确语法。dateadded<'2013-01-04 22:01:17'-第1extra行的间隔36小时限制0,30'）”。似乎有效。选择COUNT（*）FROM parts LEFT JOIN binaries ON binaries.ID=parts.binaryID LEFT JOIN releasefo rn ON rn.binaryID=binaries.ID，其中binaries.procstat IN（4,6）和（rn.binaryID为NULL或（rn.binaryID不为NULL且rn.info不为NULL））或binaries.dateadded<'2013-01-04 22:01:17'-间隔36小时；更新你的删除查询，它也有额外的“）”从你的查询中删除额外的括号

$limit = 10000; // Do in batches to give user status            
$totalRows = $db->query("Count query goes here");

while($rowsLeft > 0)
{
    echo "$rowsLeft remaining to be deleted\n";
    $db->query("DELETE ...... LIMIT ".$limit);
    $rowsLeft -= $limit;
}   

SELECT * FROM parts p 
LEFT JOIN binaries b ON b.ID = p.binaryID AND b.procstat IN (4, 6) 
LEFT JOIN releasenfo rn ON rn.binaryID = b.ID 
WHERE rn.binaryid IS NULL OR (rn.binaryid IS NOT NULL AND rn.nfo IS NOT NULL) OR 
        b.dateadded < '2013-01-04 22:01:17' - INTERVAL 36 HOUR;

DELETE p, b FROM parts p 
LEFT JOIN binaries b ON b.ID = p.binaryID AND b.procstat IN (4, 6) 
LEFT JOIN releasenfo rn ON rn.binaryID = b.ID 
WHERE rn.binaryid IS NULL OR (rn.binaryid IS NOT NULL AND rn.nfo IS NOT NULL) OR 
        b.dateadded < '2013-01-04 22:01:17' - INTERVAL 36 HOUR;