I'm honestly not sure why I'm getting an error since I just moved the two selects to be distrinct and in the left outer join but they were working before in the main opening select statement
SELECT body, timestamp FROM chats
LEFT OUTER JOIN messages ON chats.id = messages.chat_id
LEFT OUTER JOIN (SELECT DISTINCT sender.first_name AS sender_first_name, sender.last_name AS sender_last_name,
sender.username AS sender_username) users AS sender ON chats.from_user_id = sender.id
LEFT OUTER JOIN (SELECT DISTINCT reciever.first_name AS reciever_first_name, reciever.last_name AS reciever_last_name,
reciever.username AS reciever_username) users AS reciever ON chats.to_user_id = reciever.id
WHERE from_user_id = :fromUserId AND to_user_id = :toUserId
Also tried doing it with the FROM clause
LEFT OUTER JOIN (SELECT DISTINCT sender.first_name AS sender_first_name, sender.last_name AS sender_last_name,
sender.username AS sender_username FROM users) users AS sender ON chats.from_user_id = sender.id
This is not a valid subquery:
(SELECT DISTINCT sender.first_name AS sender_first_name, sender.last_name AS sender_last_name,
sender.username AS sender_username) users AS sender
You haven't explained what the query is supposed to be doing, but I speculate that you want:
SELECT body, timestamp,
us.first_name AS sender_first_name, us.last_name AS sender_last_name, us.username AS sender_username
ur.first_name AS receiver_first_name, ur.last_name AS receiver_last_name, ur.username AS receiver_username
FROM chats c LEFT OUTER JOIN
messages m
ON c.id = m.chat_id LEFT OUTER JOIN
users us
ON c.from_user_id = us.id LEFT OUTER JOIN
users ur
ON c.to_user_id = ur.id
WHERE c.from_user_id = :fromUserId AND c.to_user_id = :toUserId;
You should not need DISTINCT when joining to a table on the id.
Related
I have two tables (msg and users). I am trying to join these two tables together and print out the first and last name of the sender and the recipient as well as all of the message content if the message is marked as flag. I keep getting errors though, and have not found a good way to do this yet.
Pictures of tables for reference: https://imgur.com/a/wYuptfR
SQL query I'm using right now:
SELECT msg.*, users.uuid AS users.ruuid, users.uuid AS users.suuid, users.firstName, users.lastName
FROM msg
INNER JOIN users ON users.ruuid = msg.recipient
AND INNER JOIN users ON users.suuid = msg.sender
WHERE msg.flag = 0
You can query the same table several times if you use different aliases. Also, note you shouldn't have an and between the two join clauses:
SELECT msg.*,
r.uuid AS ruuid, r.firstName AS rfirstname, r.lastName AS rlastname,
s.uuid AS suuid, s.firstName AS sfirstname, s.lastName AS slastname
FROM msg
INNER JOIN users r ON r.uuid = msg.recipient
INNER JOIN users s ON s.uuid = msg.sender
WHERE msg.flag = 0
Try This
SELECT msg.*, u.uuid , u.firstName, u.lastName, s.uuid , s.firstName, s.lastName
FROM msg
INNER JOIN users u ON u.uuid = msg.recipient
INNER JOIN users s ON s.uuid = msg.sender
WHERE msg.flag = 0
i'm trying to build a chat application, in which i have these four tables
chat --id,group_id,body,time_posted[timestamp]
chat_groups --establish id,name for a group
users_groups --link users to a group, also define if user stared this group FIELDS::user_id,group_id,stared[bool]
wall_visit --user_id,group_id,last_visit[timestamp]
the idea is every users join a group, and they post to it in chat.
chat_groups table is just for defining the room, while users_groups is for setting access of members to this group.
wall_visit table is a table that store specific user last time accessed specific group (since its many to many u know..)
now what im trying to establish is to get in one query,
the chat_groups the user in relation with
the count of messages posted to this group since user last login (from settings)
the count of members in this group
the group name
:)
i have been trying to hours now :( best i could come up with
SELECT w.last_visit,access.stared,cg.user_id,u.fullname as username,cg.name as group_name ,cgu.count_members,c.count_msgs,c.time_posted
FROM `chat_groups`cg
inner join chat_groups_users access on (access.group_id = cg.id and access.user_id = ?)
left outer join users u on u.id = cg.user_id
left join wall_visit w on w.group_id = cg.id
left join (select count(*) as count_members,group_id from group_users group by group_id) cgu on cgu.group_id = cg.id
left join (SELECT count(wv.id) as count_msgs,c.group_id,c.time_posted FROM chats c
left outer join `wall_visit` wv on (wv.group_id is not null and c.group_id = wv.group_id and c.time_posted > wv.last_visit)
group by c.group_id) c on c.group_id = cg.id
where cg.user_id = 1
this query is working ..ehh, my main problem is with the count of the messages in the group since last_visit.
what is the best methode to get message_count to work :( ??
can this query be optimized more?
Thanks SO community :)
My 2nd attempt
SELECT w.last_visit,access.stared,cg.user_id,u.fullname as username,cg.with_id,uu.fullname as with_name,cg.name as group_name ,cgu.count_members,c.count_msgs,c.time_posted
FROM `chat_groups`cg
inner join chat_groups_users access on (access.group_id = cg.id and access.user_id = 1)
left outer join users u on u.id = cg.user_id
left join wall_visit w on w.chat_id = cg.id
left outer join users uu on uu.id = cg.with_id
left join (select count(*) as count_members,group_id from chat_groups_users group by group_id) cgu on cgu.group_id = cg.id
left join (
SELECT group_id,count(c.id) as count_msgs,time_posted FROM `chats` c inner join wall_Visit wv on wv.chat_id = c.group_id where c.id > wv.last_visit group by c.group_id
) c on c.group_id = cg.id
where cg.user_id = 1
this should fix you count message problem
SELECT
`cg`.`user_id`, `cg`.`with_id`, `cg`.`name` AS `group_name`,
`access`.`stared`,
`u`.`fullname` AS `username`,
`w`.`last_visit`,
`uu`.`fullname` AS `with_name`,
`cgu`.`count_members`,
`c`.`count_msgs`, `c`.`time_posted`
FROM `chat_groups` AS `cg`
INNER JOIN `chat_groups_users` AS `access`
ON (`access`.`group_id` = `cg`.`id` AND `access`.`user_id` = `cg`.`user_id`)
LEFT OUTER JOIN `users` AS `u`
ON (`u`.`id` = `cg`.`user_id`)
LEFT JOIN `wall_visit` AS `w`
ON (`w`.`chat_id` = `cg`.`id`)
LEFT OUTER JOIN `users` AS `uu`
ON (`uu`.`id` = `cg`.`with_id`)
LEFT JOIN (
SELECT COUNT(*) AS `count_members`, `group_id`
FROM `chat_groups_users`
GROUP BY
`group_id`
) AS `cgu`
ON (`cgu`.`group_id` = `cg`.`id`)
LEFT JOIN (
SELECT count(`c`.`id`) AS `count_msgs`, `c`.`time_posted`
FROM `chats` AS `c`
INNER JOIN `wall_visit` AS `wv`
ON (`wv`.`chat_id` = `c`.`group_id`)
WHERE
`c`.`time_posted` > `wv`.`last_visit`
GROUP BY
`c`.`group_id`
) AS `c`
ON (`c`.`group_id` = `cg`.`id`)
WHERE `cg`.`user_id` = 1
otherwise u have to setup a fiddle
I'm trying to get MySQL to return me all instructors who don't have a booking at a certain time. This query is essentially the search query. So return all instructors and their details that aren't already booked basically. Could someone help me finish it off?
SELECT
AddressTypes.AddressTypeName,
Addresses.*,
InstructorSettings.*,
Users.*,
BookedSlots.DateTime
FROM Users
LEFT OUTER JOIN InstructorSettings
ON Users.UserID = InstructorSettings.UserID
LEFT OUTER JOIN Addresses
ON Users.UserID = Addresses.UserID
INNER JOIN AddressTypes
ON Addresses.AddressTypeID = AddressTypes.AddressTypeID
LEFT OUTER JOIN BookedSlots
ON Users.UserID = BookedSlots.UserID
WHERE Users.AccountTYpe = 3 AND Addresses.PostCode1 IN ('l13') AND BookedSlots.DateTime <> '2013-04-25 11:00:00'
The query above doesn't return anything, but if I take out the "AND BookedSlots.DateTime <> '2013-04-25 11:00:00'" it returns all the instructors details fine.
Database
It looks to me as if what you're looking for is the lack of existence of records in BookedSlots for the specified time.
I'm not sure if this is considered MySQL best practices, but I typically accomplish that task not with a join, but with a sub-select or a temp table, like so:
SELECT
AddressTypes.AddressTypeName,
Addresses.*,
InstructorSettings.*,
Users.*,
FROM Users
LEFT OUTER JOIN InstructorSettings
ON Users.UserID = InstructorSettings.UserID
LEFT OUTER JOIN Addresses
ON Users.UserID = Addresses.UserID
INNER JOIN AddressTypes
ON Addresses.AddressTypeID = AddressTypes.AddressTypeID
WHERE Users.AccountType = 3 AND Addresses.PostCode1 IN ('l13')
AND Users.UserID not in (SELECT BookedSlots.InstructorID FROM BookedSlots
WHERE BookedSlots.DateTime = '2013-04-25 11:00:00')
EDIT: per comments, changed the select statement to disclude BookedSlots, and the sub-select to return InstructorId (which matches instructors instead of students on the booking).
To check that there aren't any bookings on a particular timeslot, include the timeslot in the join conditions and select where the timeslot id is null - like so:
SELECT
AddressTypes.AddressTypeName,
Addresses.*,
InstructorSettings.*,
Users.*,
BookedSlots.DateTime
FROM Users
LEFT OUTER JOIN InstructorSettings
ON Users.UserID = InstructorSettings.UserID
LEFT OUTER JOIN Addresses
ON Users.UserID = Addresses.UserID
INNER JOIN AddressTypes
ON Addresses.AddressTypeID = AddressTypes.AddressTypeID
LEFT OUTER JOIN BookedSlots
ON Users.UserID = BookedSlots.UserID AND
BookedSlots.DateTime = '2013-04-25 11:00:00'
WHERE Users.AccountTYpe = 3 AND
Addresses.PostCode1 IN ('l13') AND
BookedSlots.UserID is null
I have 3 MySQL tables namely chat_comments, chat_friends and user_details and I want to display a friend list.
My tables:
chat_comments(comment_id,comment,user_id,user_id2,date_added)
chat_friends(user_id,user_id2,approved)
user_details(user_id, mainimage_id, fullname)
To do this, I need a query that will return the needed fields (u.mainimage_id, u.fullname, b.comment, b.user_id) so I can loop through the list to display a table.
SQL so far (help from #Andriy M):
SELECT
cc.comment,
cc.date_added,
u.fullname,
u.mainimage_id
FROM
user_details u
LEFT JOIN
chat_comments cc
INNER JOIN (
SELECT
user_id,
MAX(comment_id) AS maxcomment
FROM chat_comments WHERE user_id=2020 OR user_id2=2020
GROUP BY user_id
) a ON a.user_id = cc.user_id
AND a.maxcomment = cc.comment_id
ON a.user_id = u.user_id
WHERE u.user_id IN (
SELECT user_id2
FROM chat_friends
WHERE user_id = 2020
AND approved = 1
)
The above query returns the last comment made by the logged-in user's friends in conversation not the last comment between the logged-in user and his/her friend regardless of who made it.
I would like it to return the last comment between the logged-in user and their friend individually regardless of who made it. In the chat_messages table, user_id is the sender and user_id2 is the receiver. Hope it makes sense?
Like #imm said in a comment, you need to use an outer join. In case of a left join, the user_details table should become the left side of the join, the right side being the result of your inner join of chat_comments with your a derived table. You'll also need to remove the user_id IN (…) condition from inside the a subselect and re-apply it to the user_details table. Here:
SELECT
cc.comment,
cc.date_added,
u.fullname,
u.mainimage_id
FROM
user_details u
LEFT JOIN
chat_comments cc
INNER JOIN (
SELECT
user_id,
MAX(comment_id) AS maxcomment
FROM chat_comments
GROUP BY user_id
) a ON a.user_id = cc.user_id
AND a.maxcomment = cc.comment_id
ON a.user_id = u.user_id
WHERE u.user_id IN (
SELECT user_id2
FROM chat_friends
WHERE user_id = 2020
AND approved = 1
)
;
Alternatively, you could use a right join. In this case you would just need to move the user_id IN (…) condition, similarly to the LEFT JOIN solution above, and replace the second INNER JOIN with RIGHT JOIN:
SELECT
cc.comment, cc.date_added, u.fullname, u.mainimage_id
FROM
(
SELECT user_id, MAX(comment_id) AS maxcomment
FROM chat_comments
GROUP BY user_id
) a
INNER JOIN
chat_comments cc ON
a.user_id = cc.user_id AND
a.maxcomment = cc.comment_id
RIGHT JOIN
user_details u ON
a.user_id = u.user_id
WHERE u.user_id IN (select user_id2 from chat_friends where user_id=2020 AND approved=1)
I looked at the answers of others having the same problem, but I can't figure out how to fix the "Not unique table/alias".
SELECT m.*, u.*
FROM ".TABLE_PREFIX."users_medals u
LEFT JOIN ".TABLE_PREFIX."medals m ON u.medal_id = m.medal_id
WHERE u.user_id IN (".$post['uid'].")
AND m.medal_level = (
SELECT MAX(".TABLE_PREFIX."medals.medal_level) FROM ".TABLE_PREFIX."medals
LEFT JOIN ".TABLE_PREFIX."medals ON ".TABLE_PREFIX."users_medals.medal_id = ".TABLE_PREFIX."medals.medal_id
WHERE ".TABLE_PREFIX."users_medals.user_id = u.user_id
AND ".TABLE_PREFIX."medals.medal_type = m.medal_type
)
TABLE_PREFIX is what my script uses to define the database table prefix.
In your sub-query
LEFT JOIN ".TABLE_PREFIX."medals
I think that should be
LEFT JOIN ".TABLE_PREFIX."users_medals
In the subquery you have two medals tables without aliases. I think the FROM ".TABLE_PREFIX."medals should be FROM ".TABLE_PREFIX."users_medals:
SELECT m.*, u.*
FROM ".TABLE_PREFIX."users_medals u
LEFT JOIN ".TABLE_PREFIX."medals m ON u.medal_id = m.medal_id
WHERE u.user_id IN (".$post['uid'].")
AND m.medal_level = (
SELECT MAX(".TABLE_PREFIX."medals.medal_level) FROM ".TABLE_PREFIX."users_medals
LEFT JOIN ".TABLE_PREFIX."medals ON ".TABLE_PREFIX."users_medals.medal_id = ".TABLE_PREFIX."medals.medal_id
WHERE ".TABLE_PREFIX."users_medals.user_id = u.user_id
AND ".TABLE_PREFIX."medals.medal_type = m.medal_type
)