MySQL和php PDO如何获取:SELECT EXISTS(SELECT 1 FROM x WHERE y =:value)

Question

我正在使用这种语法而不是count(*)因为它应该更快但我不知道如何获取结果输出

$alreadyMember = $dataBase->prepare('SELECT EXISTS ( SELECT 1 
FROM TheCommunityReachLinkingTable 
WHERE communityKey = :communityKey 
AND userID = :userID)');
$alreadyMember->bindParam(':communityKey', $_POST['communityKey'], PDO::PARAM_STR);
$alreadyMember->bindParam(':userID', $_POST['userID'], PDO::PARAM_INT);
$alreadyMember->execute();

if($alreadyMember->fetch()) {do code here} 

但它似乎没有返回正确的东西,任何想法？

Answer 1

这里的使用EXISTS似乎不对.只需执行此查询:

SELECT 1 
FROM TheCommunityReachLinkingTable 
WHERE communityKey = :communityKey 
AND userID = :userID