好。我终于为我的php文件写了查询（它将查询写到txt文件）。但是，当我较早地测试文件时，我显然要花费最大的执行时间。我只使用一个大查询来完成工作，但是现在我想知道是否最好使用多个较小的查询。这样会减少执行时间吗？
如果可以的话，那么我对所有人还有另一个问题，我将如何处理？这是我文件的大部分：
// Query the database for data
$query = "SELECT
cards.card_id,
concat(cards.title, ' By Amy') AS cardTitle,
cards.meta_description,
cards.description,
'' as Weight,
'' as UPC,
cards.seo_keywords,
concat('http://www.amyadele.com/attachments//cards/',cards.card_id,'/',cards.card_image) AS ImageURL,
card_import.artist,
concat('ARTIST - ', card_import.artist) AS Brand,
min(card_lookup_values.card_price) AS LowPrice,
replace(lower(concat( 'http://www.amyadele.com/', pcat.seoname,'/',cat.seoname, '/', cards.seoname, '.htm' )),' ','+') AS link,
concat(pcat.name,'>',cat.name) as Merchant,
round(min(card_lookup_values.card_price), 2) AS newPrice,
min(cast(lookup_details.value as signed)) as quantity
FROM
cards
INNER JOIN card_cheapest on cards.card_id = card_cheapest.card_id
LEFT JOIN card_import on card_import.card_id = cards.card_id
INNER JOIN card_lookup_values on card_lookup_values.card_id = cards.card_id
INNER JOIN card_categories cc ON cards.card_id = cc.card_id AND cards.card_live = 'y' AND cards.active = 'y' AND cc.active = 'Y'
INNER JOIN categories cat ON cat.category_id = cc.category_id AND cat.active = 'Y'
INNER JOIN categories pcat ON cat.parent_category_id = pcat.category_id
INNER JOIN card_lookup_values as card_values ON cards.card_id = card_values.card_id
INNER JOIN lookup_details ON card_lookup_values.lookup_detail_id = lookup_details.lookup_detail_id
WHERE card_lookup_values.lookup_id = 7
GROUP BY
cards.card_id
ORDER BY
cards.card_id";
$result = mysql_query($query);
// Open file for writing
$myFile = "google.txt";
$fh = fopen($myFile, 'w') or die("can't open file");
// Loop through returned data and write (append) directly to file
fprintf($fh, "%-25s %-200 \n", "ID", "Name");
fprintf($fh, "\n");
while ($row = mysql_fetch_assoc($result)) {
fprintf($fh, "%-25s %-200s \n", $row['card_id'], $row['cardTitle']);
}
// Close out the file
fclose($fh);
echo "The file has been written sucessfully to googleproducts.txt. It will run again tomorrow at 12:00pm."
?>
如您所见，我将$ query放入$ results，然后将其插入到$ row中。我猜我的实际问题（如果可能的话），我该如何处理$ query和$ query2并将$ query2插入同一while语句中？
最佳答案
多个查询（如果有的话）只会减慢速度。这意味着编译/执行多个查询，因此最终会产生更多开销。在查询中使用explain可以查看正在使用（和不使用）的索引，并在需要时添加更多索引。在某些情况下，事情自然会很慢。毕竟，您要对7个表进行8路联接。
检查索引使用情况的明显位置：where和join子句中的每个字段。