[英]php PDO MySQL Select results of one table based on array of results from another table
以下查询将返回所有“阻止者”用户和所有“阻止”用户。 相当直接的查询。
$stmt=$db->prepare('SELECT blocker,blocked FROM list_blocked
WHERE (blocked = :username AND blocker <> :username)
OR (blocker = :username AND blocked <> :username)');
$stmt->bindParam(':username', $username);
$stmt->execute();
下一个查询将返回成员表中除当前$ username之外的所有用户名。
$query = $db->prepare("SELECT username FROM members WHERE username <> :username");
$query->bindValue(':user', $username;
$query->execute();
$row = $query->fetchAll();
我需要的是一种从第一个查询的结果中获取所有值的方法,不包括活动的$ username,然后从第二个查询中排除所有这些结果。
因此,例如:
Example results of first query:
jim blocked joe
larry blocked joe
steve blocked joe
joe blocked tony
jack blocked joe
Those results applied to the second query would look something like:
$query = $db->prepare("SELECT username FROM members WHERE username <> :username
AND username <> jim
AND username <> larry
AND username <> steve
AND username <> tony
AND username <> jack");
我究竟将如何实现这样的目标?
更新:
因此,我尝试使用子查询,但它不断返回“操作数应包含1列”
SELECT username FROM members WHERE username NOT IN (
SELECT blocker,blocked FROM list_blocked
WHERE (blocked = 'viraladmin' AND blocker <> 'viraladmin')
OR (blocker = 'viraladmin' AND blocked <> 'viraladmin')
)
另一个更新:
我尝试使用内部联接来实现此目的,但是结果总是返回空,我认为这是因为实际上没有任何联接。
SELECT members.username, list_blocked.blocker, list_blocked.blocked
FROM members
INNER JOIN list_blocked
ON members.username = list_blocked.blocker
AND members.username = list_blocked.blocked
WHERE members.username <> 'username'
AND (list_blocked.blocked = 'username' AND list_blocked.blocker <> 'username')
OR (list_blocked.blocker = 'username' AND list_blocked.blocked <> 'username')
您可以使用子查询来完成此操作:
SELECT username FROM members WHERE username NOT IN (
SELECT blocker,blocked FROM list_blocked
WHERE (blocked = :username AND blocker <> :username)
OR (blocker = :username AND blocked <> :username)
)
已编辑-为了适合SQL查询,您需要在子查询中进行合并,以便返回的结果不超过一栏。 :
SELECT username FROM members WHERE username NOT IN (
SELECT blocker as username FROM list_blocked
WHERE (blocked = :username AND blocker <> :username)
OR (blocker = :username AND blocked <> :username)
UNION
SELECT blocked as username FROM list_blocked
WHERE (blocked = :username AND blocker <> :username)
OR (blocker = :username AND blocked <> :username)
)
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