I have below query running on my users and chats table to join and I'm trying to group by on my chats table for user_id OR receiver_id not just user_id like you can see below in SQL query inside INNER JOIN.
SELECT c.*, users.username, users.firstname, users.lastname
FROM chats c
INNER JOIN( SELECT MAX(created) AS Date, user_id, receiver_id, chat, type, id
FROM chats
WHERE receiver_id = 286 OR user_id = 286
GROUP BY user_id ) cc ON cc.Date = c.created AND cc.user_id = c.user_id
LEFT JOIN users ON users.id = c.user_id
WHERE c.receiver_id = 286 OR c.user_id = 286
I tried GROUP BY user_id OR receiver_id but I can't seem to get information for id 286 for either receiver_id or user_id.
Is there a way we can achieve it and group by so that we can look into both columns and come up with results from both?
Do I need to do two queries and join them together instead?
If you are looking for most recent chat record, why don't you just sort the results by created and get the first row like this:
SELECT c.*, users.username, users.firstname, users.lastname
FROM chats c, users u
WHERE (c.receiver_id = 286 OR c.user_id = 286) AND
u.id = c.user_id
ORDER BY created DESC
LIMIT 1
Related
I am trying to use the following code to get the 6 users with which the current user has most recently chatted. I have two problems. First of all, if the current user has recieved a message from the other user but has only sent, that other user isnt fetched. Second of all, the ORDER BY clause is causing an error. Im a beginner in SQL so I have no idea what's going on.
Thanks in Advance!
Here's the code:
SELECT users.*
FROM users INNER JOIN
messages fromuser
ON (fromuser.fromid = users.id) INNER JOIN
messages touser
ON (touser.toid = users.id)
WHERE fromuser.toid = :userid OR touser.fromid = :meid
GROUP BY users.id
ORDER BY MAX(messages.datetime)
LIMIT 6;
This should do your job, and it relies less on MySQL extensions than your other answer so far. I estimate that it would perform about the same, but it's surely wordier.
SELECT u.*
FROM (
SELECT DISTINCT otherid
FROM (
SELECT
m.fromid AS otherid,
MAX(m.datetime) as maxts
FROM messages m
WHERE m.toid = :userid
GROUP BY m.fromid
UNION ALL
SELECT
m.toid AS otherid,
MAX(m.datetime) as maxts
FROM messages m
WHERE m.fromid = :userid
GROUP BY m.toid
) um
ORDER BY maxts DESC
LIMIT 6
) otheru
INNER JOIN users u
ON u.id = otheru.otherid
Your logic is doomed to fail, because one users.id cannot be two different values at the same time. I think this query does what you want:
SELECT u.*
FROM messages m INNER JOIN
users u
ON (m.fromid = u.id AND m.toid = :userid) OR
(m.toid = u.id AND m.fromid = :userid )
GROUP BY u.id
ORDER BY MAX(m.datetime) DESC
LIMIT 6;
Notice that it joins to the users table by the id that is not the current user.
I've this table structure:
-request
request_id
user_id
-user
user_id
company_id
-company
company_id
I want to select all those records from requests table where user_id=? and no such records where the company id of to users is same.
This is usually achieved using LEFT JOIN:
SELECT r.*
FROM request r
JOIN user u ON r.user_id = u.user_id
LEFT JOIN u1 ON u1.user_id != u.user_id AND u1.company_id = u.company_id
LEFT JOIN request r1 ON r1.user_id = u1.user_id
WHERE r1.user_id IS NULL
By "where" we say that we don't want "users with same company, who has at least 1 request"
I have two table, users and comments.
In the users table, there're columns id and username.
In the comments table I have user_id and his message.
And I wanted to create a table that select the username and his comment count when I search a particular username.
How do I write this?
my testing attempt:
SELECT COUNT(*) AS comment_count
FROM song_comments
RIGHT JOIN users
WHERE user_id = 7 AND comments.user_id = users.id
Try this:
SELECT U.Username, COUNT(SC.message) AS comment_count
FROM song_comments SC JOIN
users U ON U.id=SC.user_id
WHERE U.user_id = 7
GROUP BY U.Username
This gives you users and count
select u.username, count(c.user_id) as comment_count
from users u
join comments c on u.id = c.user_id
group by u.username
You can add a where to get one user's count
select u.username, count(c.user_id) as comment_count
from users u
join comments c on u.id = c.user_id
where u.username = 'Hogan'
group by u.username
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 have two tables:
users:
user_id user_name
data:
user_id user_data user_time
I wan to select the latest entry from the data table, but return the user_name, user_id, user_data and user_time.
I have tried the following query, but it returns the first entry, not the last for each user:
sql = "SELECT users.user_name, users.user_id, data.user_data, data.user_time
FROM users
INNER JOIN data ON data.user_id = users.user_id
GROUP BY users.user_name
ORDER BY data.user_time DESC";
Use GROUP BY and MAX, WHERE...IN:
SELECT u.user_id, u.user_name, d.user_data, d.user_time
FROM users u
INNER JOIN data d ON d.user_id = u.user_id
WHERE (d.user_id, d.user_time) =
(SELECT user_id, MAX(user_time) FROM data GROUP BY user_id)
I think you had better add data_id column to data table.
Unless data_id, both user_id and user_time are necessary for PRIMARY KEY(and user_time is not always unique, not reliable)
If there is data_id, it can be bitly simple:
SELECT u.user_id, u.user_name, d.user_data, d.user_time
FROM users u
INNER JOIN data d ON d.data_id =
(SELECT data_id FROM data
WHERE user_id = u.user_id ORDER BY data_time DESC LIMIT 1)