串联中的附加项无法按预期工作 [英] Concatenation with addition in it doesn't work as expected
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问题描述
这是我的带有SQL查询的PHP代码,但是输出与预期不符:
Here is my PHP code with SQL query, but the output isn't as expected:
$sql = 'INSERT INTO `event_footers` (`event_id`, `order`, `file_id`, `url`) VALUES ';
foreach($all_footers as $key => $val){
$sql .= '('.(int)$data['event_id'].', '.$key + 1 .', '.(int)$val['file_id'].', "'.addslashes($val['url']).'"), ';
}
$sql = rtrim($sql, ', ');
var_dump($sql);
exit;
然后我得到这样的sql查询:
AND I get sql query like this:
`INSERT INTO `event_footers` (`event_id`, `order`, `file_id`, `url`) VALUES 1, 2135, "http://11.lt"), 1, 2136, "http://22.lt"), 1, 2140, "http://44.lt")`
在VALUES之后的第一个(
在哪里?
Where is the first (
after VALUES?
推荐答案
+
and .
have the same operator precedence, but are left associative. Means after the first concatenation:
'(' . (int)$data['event_id']
该字符串已与您的密钥添加在一起,例如
The string got added with your key, e.g.
"($data['event_id']" + $key
因此,字符串被转换为整数在这种数字背景下和消失.要解决此问题,请在您的加法周围加上括号()
.
So the string gets converted into an integer in that numerical context and disappears. To solve this use parentheses ()
around your addition.
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