我正在尝试更新较旧的 MySQL PHP 方法调用,但最终调用相同的 SELECT 调用两次以获得相同的结果。有更好的方法吗?
原文如下:
function updateProbabilities()
{
// first update the word count of each category
$rs = $this->con->select("SELECT category_id, SUM(count) AS total FROM nb_wordfreqs WHERE 1 GROUP BY category_id");
$total_words = 0;
while (!$rs->EOF()) {
$total_words += $rs->f('total');
$rs->moveNext();
}
$rs->moveStart();
if ($total_words == 0) {
$this->con->execute("UPDATE nb_categories SET word_count=0, probability=0 WHERE 1");
return true;
}
while (!$rs->EOF()) {
$proba = $rs->f('total')/$total_words;
$this->con->execute("UPDATE nb_categories SET word_count=".(int)$rs->f('total').",
probability=".$proba."
WHERE category_id = '".$rs->f('category_id')."'");
$rs->moveNext();
}
return true;
}
这是我的版本:
function updateProbabilities() {
$sql = "SELECT category_id, SUM(count) AS total FROM nb_wordfreqs WHERE 1 GROUP BY category_id";
$res = mysql_query($sql) or die (mysql_error());
$total_words = 0;
while ($row = mysql_fetch_array($res, MYSQL_ASSOC)) {
$total_words += $row['total'];
}
if ($total_words >= 1) {
$sql = "SELECT category_id, SUM(count) AS total FROM nb_wordfreqs WHERE 1 GROUP BY category_id";
$res = mysql_query($sql) or die (mysql_error());
while ($row = mysql_fetch_array($res, MYSQL_ASSOC)) {
$proba = $row['total']/$total_words;
$count = (int)$row['total'];
$sql = "UPDATE nb_categories SET word_count=".$count.",
probability=".$proba."
WHERE category_id = '".$row['category_id']."'";
mysql_query($sql) or die (mysql_error());
}
}
else {
$sql = "UPDATE nb_categories SET word_count=0, probability=0 WHERE 1";
mysql_query($sql) or die (mysql_error());
}
return true;
}
您认为有什么方法可以避免第二次重复的 SELECT 调用吗?
最佳答案
第一次运行查询时,将其添加到 while 循环中以存储结果:
$rowarray[] = $row; // added to prevent running it twice
然后第二次出现时,替换它:
$sql = "SELECT category_id, SUM(count) AS total FROM nb_wordfreqs WHERE 1 GROUP BY category_id";
$res = mysql_query($sql) or die (mysql_error());
while ($row = mysql_fetch_array($res, MYSQL_ASSOC)) {
这样:
foreach ($rowarray as $row) {
另外:远离 mysql_ 函数,因为它们已被弃用,并将很快从 PHP 中删除。更改为 PDO 或 MySQLi。您已经在更新代码,不妨也进行更改。
关于php - 我怎样才能改进这个 PHP MySQL 调用?,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/15029547/