Php 左连接mysql问题
这是我的疑问:Php 左连接mysql问题,php,mysql,join,Php,Mysql,Join,这是我的疑问: SELECT * FROM ( SELECT users.id, users.name, users.gender users.gender_preference, users.about_me FROM `users` LEFT JOIN users_purchase ON users.id = users_purchase.user_id WHERE users.id != 20 AND users.status = 1
SELECT *
FROM (
SELECT users.id, users.name, users.gender
users.gender_preference, users.about_me
FROM `users`
LEFT JOIN users_purchase ON users.id = users_purchase.user_id
WHERE users.id != 20
AND users.status = 1
AND users.birthdate <= '1996-03-18' AND users.birthdate >= '1934-03-18' AND users.gender = '2'
GROUP BY users.id
) AS myTable
我需要从我的查询结果中删除阻止程序“theBlocker”阻止的用户“whoToBlock”。
有什么想法吗
我假设whoToBlock映射到你的user.id,而blocker是一个布尔值。相应地编辑这些条件我有点不清楚谁在阻止谁。让我假设,作为您的示例,您希望排除任何被用户20阻止的用户。将其添加到查询中的一种简单方法是在where子句中:
请注意,我还删除了额外的子查询层,并添加了表别名,以使查询更具可读性。我不需要一个连接来实现此功能吗?user1331131-阻止程序是一个整数-阻止您的id。我测试了你的查询——我仍然在查询应该被阻止的用户。
id (primary),theBlocker, whoToBlock
SELECT *
FROM (
SELECT users.id, users.name, users.gender
users.gender_preference, users.about_me
FROM `users`
LEFT JOIN users_purchase ON users.id = users_purchase.user_id
LEFT JOIN OTHERTABLE ON whoToBlock = users.id
WHERE users.id != 20
AND users.status = 1
AND users.birthdate <= '1996-03-18'
AND users.birthdate >= '1934-03-18'
AND users.gender = '2'
AND OTHERTABLE.theBlocker IS NULL
GROUP BY users.id
) AS myTable
SELECT u.id, u.name, u.gender, u.gender_preference, u.about_me
FROM `users` u LEFT JOIN
users_purchase up
ON u.id = up.user_id
WHERE u.id <> 20 AND
u.status = 1 AND
u.birthdate <= '1996-03-18' AND
u.birthdate >= '1934-03-18' AND
u.gender = '2' and
NOT EXISTS (select 1
from blockers b
where b.theBlocker = 20 and b.whomToBlock = u.id
)
GROUP BY users.id;