我正在组合 MySQL 查询,以便用户可以选择多个下拉列表并根据这些下拉列表进行过滤。正如我使用 $echo 查询检查的那样,这按预期工作。但是,除了第一个单词之外,我需要在每次出现单词“WHERE”之前插入“AND”。目前,如果我选择多个下拉列表,我的查询将如下所示:
SELECT a.MembershipID,
a.FirstName,
a.Surname,
t.RaceID,
t.Time,
r.RaceID,
r.RaceName,
r.Distance,
r.ClubYear
FROM Athlete AS a
INNER JOIN Time AS t ON a.MembershipID=t.MembershipID
INNER JOIN Race AS r ON t.RaceID=r.RaceID
WHERE r.RaceName= 'Parkrun' WHERE r.Distance= '5 kilometres'
ORDER BY a.Surname
正如您在第 4 行看到的,有两个没有 AND 的 WHERE 查询。如何在第二个 WHERE 之前插入 AND?除了第一个位置之外,我如何为每个后续位置执行此操作?我考虑过使用爆炸来创建子字符串,插入 AND,然后将它们重新连接在一起,但这似乎有点过头了。有什么帮助吗? 谢谢。
编辑:添加生成上述内容的 PHP 代码:
$query = "SELECT a.MembershipID, a.FirstName, a.Surname, t.RaceID, t.Time, r.RaceID, r.RaceName, r.Distance, r.ClubYear
FROM Athlete AS a
INNER JOIN Time AS t
ON a.MembershipID=t.MembershipID
INNER JOIN Race AS r
ON t.RaceID=r.RaceID";
if ($_POST['raceName']!= null) {
$raceName = mysqli_real_escape_string($mysqli, $_POST["raceName"]);
$filter = " WHERE r.RaceName= '$raceName'";
$query .= $filter;
}
if ($_POST['athlete']!= null) {
$athlete = mysqli_real_escape_string($mysqli, $_POST["athlete"]);
$firstWord = explode(' ',trim($athlete));
$firstName = $firstWord[0];
$lastWord = explode(' ', $athlete);
$surname = array_pop($lastWord);
$filter = " WHERE a.FirstName= '$firstName' AND a.Surname = '$surname'";
$query .= $filter;
}
if ($_POST['distance']!= null) {
$distance = mysqli_real_escape_string($mysqli, $_POST["distance"]);
$filter = " WHERE r.Distance= '$distance'";
$query .= $filter;
}
if ($_POST['clubYear']!= null) {
$clubYear = mysqli_real_escape_string($mysqli, $_POST["clubYear"]);
$filter = " WHERE r.ClubYear= '$clubYear'";
$query .= $filter;
}
$fullquery = $query . " ORDER BY a.Surname";
最佳答案
一个简单的解决方案是首先添加一个始终为 true 的语句,例如 1=1
,这样您就不必检查它是否是第一个语句,然后通过附加来继续构建查询相应地和CONDITION_N
$query = "SELECT a.MembershipID, a.FirstName, a.Surname, t.RaceID, t.Time, r.RaceID, r.RaceName, r.Distance, r.ClubYear
FROM Athlete AS a
INNER JOIN Time AS t
ON a.MembershipID=t.MembershipID
INNER JOIN Race AS r
ON t.RaceID=r.RaceID";
$query .= " WHERE 1 = 1 ";
if ($_POST['raceName']!= null) {
$raceName = mysqli_real_escape_string($mysqli, $_POST["raceName"]);
$filter = " AND r.RaceName= '$raceName'";
$query .= $filter;
}
说明:
- 如果没有或您的
if
条件为 true,则您的查询将是您最初的查询WHERE 1=1
所遵循的任何内容,这与没有它完全相同第一名 如果您的任何条件
为真
,则为:INITIAL_QUERY WHERE 1=1 AND CONDITION_N
如果多个条件成立,则为:
INITIAL_QUERY WHERE 1=1 AND CONDITION_N AND CONDITION_N+1
这使您的 PHP 代码更干净、更快,因为您不必检查它是否是第一个条件来决定是使用 WHERE
还是 AND
当附加到您的 select 语句时
关于php - 在另一个字符串中的某个单词之前插入字符串,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/26562126/