我写了一个MySQL查询：
$feedItem->tags =
$result = mysqli_query("SELECT *
FROM qzxh_k2_tags, qzxh_k2_tags_xref
WHERE qzxh_k2_tags.id = qzxh_k2_tags_xref.tagID
AND qzxh_k2_tags.id = '406'
AND qzxh_k2_tags_xref.itemID = '".$item->id"'");
while($tag = mysqli_fetch_array($result))
echo $tag;
查询本身显示了我在 PHPMyAdmin 中需要的结果，但由于某种原因，它在 PHP 中使用时没有显示任何内容。有什么想法我哪里出错了？
您缺少串联运算符（点）
改变
"SELECT *
FROM qzxh_k2_tags, qzxh_k2_tags_xref
WHERE qzxh_k2_tags.id = qzxh_k2_tags_xref.tagID
AND qzxh_k2_tags.id = '406'
AND qzxh_k2_tags_xref.itemID = '".$item->id"'"
// You are missing dot . here ^
自
"SELECT *
FROM qzxh_k2_tags, qzxh_k2_tags_xref
WHERE qzxh_k2_tags.id = qzxh_k2_tags_xref.tagID
AND qzxh_k2_tags.id = '406'
AND qzxh_k2_tags_xref.itemID = '".$item->id."'"
在 sql 查询中使用正确的字符串连接。在下面找到更正的查询。
$result = mysqli_query("SELECT *
FROM qzxh_k2_tags, qzxh_k2_tags_xref
WHERE qzxh_k2_tags.id = qzxh_k2_tags_xref.tagID
AND qzxh_k2_tags.id = '406'
AND qzxh_k2_tags_xref.itemID = '".$item->id."'");