Question

我有一个查询，其中我正在使用WHERE子句。

我的查询：

SELECT * FROM notifications WHERE recipient= '".$_SESSION['id']."' AND viewed >  
'".$twoweeksago."' OR viewed IS NULL ORDER BY recieved DESC

基本上，查询选择收件人是用户登录的所有数据行，并且查看的是不到两周的日期（$ twoweeksago是我脚本中设置的变量）。但是，查看列的默认值为0000-00-00 00:00:00，所以我不得不使用：

OR viewed IS NULL

这会产生问题。我认为这是一个仅适用于先前条件的条件，即：

 AND viewed > '".$twoweeksago."'

但是，它实际上是整个WHERE子句的OR，并且阻止了所有先前的条件。如何编写仅影响AND查看的OR条件＆gt; ' “$ twoweeksago。”'

谢谢！

Answer 1

您应该将条件包装在这样的括号中：

SELECT * FROM notifications WHERE recipient= '".$_SESSION['id']."' AND (viewed > '".$twoweeksago."' OR viewed IS NULL) ORDER BY recieved DESC

这应该有用。

作为旁注，您应该记住不要直接从用户使用变量，因为它可以引入安全后膛。

Answer 2

您应该在分组子句周围添加括号：

SELECT * FROM notifications WHERE recipient= '".$_SESSION['id']."' AND (viewed >  '".$twoweeksago."' OR viewed IS NULL) ORDER BY recieved DESC

Answer 3

SELECT * FROM notifications WHERE recipient= '".$_SESSION['id']."' AND (viewed IS NULL OR viewed > '".$twoweeksago."') ORDER BY recieved DESC

我相信这会奏效。

Answer 4

SELECT * FROM notifications
WHERE recipient= '" . $_SESSION['id'] . "'
AND (
    viewed > '" . $twoweeksago . "'
    OR viewed IS NULL
)
ORDER BY recieved DESC;

Answer 5

试试这个

SELECT * FROM notifications WHERE recipient= '".$_SESSION['id']."' AND (viewed >  
'".$twoweeksago."' OR viewed=NULL ORDER BY recieved DESC

Answer 6

SELECT *
FROM table
WHERE
receipt = session
HAVING
viewed > time OR
viewed = null
ORDER BY
sort DESC

使用Pdo你的例子看起来像这样。

$link = new PDO('mysql:host=localhost;dbname=db', 'User', 'Pass');
$entry = $link->prepare('SELECT * FROM table WHERE receipt = :session HAVING viewed > :time OR viewed = null ORDER BY received DESC');
$entry->execute(array('session' => $Session, 'time' => $Time));

使阅读更容易，更不用说了。现在你有更多的控制能力。：3 PDO赢得任何人？

使用MySQL WHERE子句

6 个答案: