alright so i've got two tables here, gforum_Post and gforum_PostView
i'm trying to get information from the table gforum_Post where it has the same post_id.
"SELECT post_subject, post_username FROM `gforum_Post` WHERE post_id = 341"
i've got it to display what i want but it's hard coded, the data in the columns will change. here's what i've got so far
SELECT post_id_fk, post_thread_views FROM `gforum_PostView` ORDER BY `gforum_PostView`.`post_thread_views` DESC
SELECT post_subject, post_username FROM `gforum_Post` WHERE post_id = 341
341 is the value that is hardcoded
You can use join to join the tables:
SELECT post_id_fk, post_thread_views, post_subject, post_username FROM `gforum_PostView`
join `gforum_Post` on post_id =post_id_fk
ORDER BY `gforum_PostView`.`post_thread_views` DESC
I think what you're looking for is the JOIN query:
SELECT GPV.post_id_fk, GPV.post_thread_views, GP.post_subject, GP.post_username
FROM gforum_Post GP, gforum_PostView GPV
WHERE GP.post_id = 341
ORDER BY GPV.post_thread_views DESC
Related
The goal is to load a list of chats where the user sending the request is a member in. Some of the chats are group chats (more than two members) and there I want to show the profile pictures from the users who wrote the last three messages.
The first query to load meta data like the title and the timestamp of the chat is:
SELECT Chat_Users.ID_Chat, Chats.title, Chats.lastMessageAt
FROM Chat_Users
JOIN Chats ON Chats.ID = Chat_Users.ID_Chat
GROUP BY Chat_Users.ID_Chat
HAVING COUNT(Chat_Users.ID_Chat) = 2
AND MAX(Chat_Users.ID_User = $userID) > 0
ORDER BY Chats.lastMessageAt DESC
LIMIT 20
The query to load the last three profile pictures from one of the chats loaded with the query above is:
SELECT GROUP_CONCAT(innerTable.profilePictures SEPARATOR ', ') AS 'ppUrls',
innerTable.ID_Chat
FROM
(
SELECT Chat_Users.ID_Chat, Users.profilePictureUrl AS profilePictures
FROM Users
JOIN Chat_Users ON Chat_Users.ID_User = Users.ID
JOIN Chat_Messages ON Chat_Messages.ID_Chat = Chat_Users.ID_Chat
WHERE Chat_Users.ID_Chat = $chatID
ORDER BY Chat_Messages.timestamp DESC
LIMIT 3
) innerTable
GROUP BY innerTable.ID_Chat
Both are working separately but I want to merge them together so I don't have to run the second query in a loop due to performance reasons. Unfortunately I have no idea how this can be achieved because the second query needs the $chatID, which it only gets from the first query.
So to clarify the desired result: The list with the profile picture urls (second query) should be just another column in the result of the first query.
I hope it is explained in a reasonably understandable way. Any help would be much appreciated.
Edit: Sample data from the affected tables:
Table "Chats":
Table "Chat_Users":
Table "Chat_Messages":
Table "Users":
This fufils the brief, however it requires a view because MySQL 5.x doesn't support the WITH clause.
It's long and cluncky and I've tried to shorten it but this is as good as I can get, hopefully someone will pop up in the comments with a way to make it shorter!
The view:
CREATE VIEW last_interaction AS
SELECT
id_chat,
id_user,
MAX(timestamp) AS timestamp
FROM chat_messages
GROUP BY id_user, id_chat
The query:
SELECT
Chat_Users.ID_Chat,
Chats.title,
Chats.lastMessageAt,
urls.pps AS profilePictureUrls
FROM Chat_Users
JOIN Chats ON Chats.ID = Chat_Users.ID_Chat
JOIN (
SELECT
lo.id_chat,
GROUP_CONCAT(users.profilePictureUrl) AS pps
FROM last_interaction lo
JOIN users ON users.id = lo.id_user
WHERE (
SELECT COUNT(*) -- the amount of more recent interactions
FROM last_interaction li
WHERE (li.timestamp = lo.timestamp AND li.id_user > lo.id_user)
) < 3
GROUP BY id_chat
) urls ON urls.id_chat = Chats.id
GROUP BY Chat_Users.ID_Chat
HAVING COUNT(Chat_Users.ID_Chat) > 2
AND MAX(Chat_Users.ID_User = $userID)
ORDER BY Chats.lastMessageAt DESC
LIMIT 20
My MySQL query is loading very slow (over 30 secs), I was wondering what tweaks I can make to optimize it.
The query should return the last post with the string "?" of all threads.
SELECT FeedbackId, ParentFeedbackId, PageId, FeedbackTitle, FeedbackText, FeedbackDate
FROM ReaderFeedback AS c
LEFT JOIN (
SELECT max(FeedbackId) AS MaxFeedbackId
FROM ReaderFeedback
WHERE ParentFeedbackId IS NOT NULL
GROUP BY ParentFeedbackId
) AS d ON d.MaxFeedbackId = c.FeedbackId
WHERE ParentFeedbackId IS NOT NULL
AND FeedbackText LIKE '%?%'
GROUP BY ParentFeedbackId
ORDER BY d.MaxFeedbackId DESC LIMIT 50
Before discuss this problem, I have formatted your SQL:
SELECT feedbackid,
parentfeedbackid,
pageid,
feedbacktitle,
feedbacktext,
feedbackdate
FROM readerfeedback AS c
LEFT JOIN (SELECT Max(feedbackid) AS MaxFeedbackId
FROM readerfeedback
WHERE parentfeedbackid IS NOT NULL
GROUP BY parentfeedbackid) AS d
ON d.maxfeedbackid = c.feedbackid
WHERE parentfeedbackid IS NOT NULL
AND feedbacktext LIKE '%?%'
GROUP BY parentfeedbackid
ORDER BY d.maxfeedbackid DESC
LIMIT 50
Since there is an Inefficient query criteria in your SQL:
feedbacktext LIKE '%?%'
Which is not able to take benefit from Index and needs a full scan, I suggest you to add a new field
isQuestion BOOLEAN
to your table, and then add logic in your program to assign this field when insert/update a feedbacktext.
Finally your can query based on this field and take benefit from index.
Firstly your SQL is not valid. The outer Group by is not valid.
According to the SQL the second group by is not needed. I moved the 2 where into inner SQL, as well as the limit, wonder if the following is quicker:
SELECT FeedbackId, ParentFeedbackId, PageId, FeedbackTitle, FeedbackText, FeedbackDate
FROM ReaderFeedback AS c
JOIN (
SELECT max(FeedbackId) AS MaxFeedbackId
FROM ReaderFeedback
WHERE ParentFeedbackId IS NOT NULL
AND FeedbackText LIKE '%?%'
GROUP BY ParentFeedbackId
ORDER BY 1 DESC LIMIT 50
) AS d ON d.MaxFeedbackId = c.FeedbackId
Please have a look at your table structure, see if there is any normalisation be downed for speed concern.
Doing a query on forum database. I am using this query to get thread name, poster, date etc.
(Left only thread_subject for now)
SELECT `thread_subject` FROM `fusion_posts` JOIN `fusion_threads`
ON fusion_posts.thread_id=fusion_threads.thread_id JOIN `fusion_users` ON
fusion_posts.post_author=fusion_users.user_id
GROUP BY fusion_posts.thread_id ORDER BY `post_id` DESC LIMIT 16
Basically, I also need to add something like the count below to the existing select, to count posts of each thread.
SELECT COUNT(*) AS PostCount FROM fusion_posts,fusion_threads WHERE fusion_threads.thread_id = fusion_posts.thread_id group by fusion_threads.thread_id
How could I do that?
Try this:-
SELECT `thread_subject`, COUNT(*) AS PostCount
FROM `fusion_posts` JOIN `fusion_threads`
ON fusion_posts.thread_id=fusion_threads.thread_id JOIN `fusion_users`
ON fusion_posts.post_author=fusion_users.user_id
GROUP BY fusion_posts.thread_id, `thread_subject`
ORDER BY `post_id` DESC
LIMIT 16
Hi guys i am new bie to MySQL,this might be
easier to question but i am totally new for mysql.
i have two tables order and shops the Desc of two
tables look like this....
OrdersTable.
order id:
ordername:
shopnum(fk)
Shopstable*
shopname:
shopnum(pk):
i am using sub query like this,to get the shops name which have most number of orders....
like...19 xyzshop
. 13 hjjddshop
. 6 reebok shop
select shopname
from shopstable
where shopnum in
(select count(orderid) as highest ,shopnum
from orderTable
group by shopnum)
it throws error,display column should be 1,its because the subquery is returning 2 results...so how do i avoid that and get the appropriate result...help will be appreciated...:):)
It's not complaining because the subquery returns 2 results but two columns. But even if it did only return a single column, it would return 2 results and the main query would do the same.
No need for a subquery in any case:
SELECT s.shopname
FROM Shopstable s
JOIN OrdersTable o ON s.shopnum=o.shopnum
GROUP BY s.shopname
ORDER BY count(*) DESC
LIMIT 1
Use this:
select shopname
from shopstable
where shopnum in
(select shopnum
from orderTable
group by shopnum
order by count(*) DESC
limit 1)
remove count(orderid) as highest , in your query. you should only select one column in your subquery
i think you want something like this...
SELECT shopname, count(*) as highest
FROM shopstable
INNER JOIN orderTable ON (shopstable = orderTable.shopname)
GROUP BY shopstable.shopname
i think this is the result you want?
I have the following 2 queries.
Query 1 :
select distinct(thread_id) from records where client_name='MyClient'
Query 2 :
select max(thread_no) from records
where thread_id='loop_result_from_above_query' AND action='Reviewed'
Is it possible to combine them into a single query ?
The second query is run on every result of the first query.
Thank you.
See attached image of a small snippet of mysql records.
I need a single mysql query to output only records which have action="MyAction" as the latest records for a given set of thread_ids. In the sample data set : record with Sr: 7201
I hope this helps in helping me :)
SELECT client_name, thread_id, MAX(thread_no) max_thread
FROM records
WHERE action='Reviewed' AND client_name='MyClient'
GROUP BY client_name, thread_id
UPDATE 1
SELECT a.*
FROM records a
INNER JOIN
(
SELECT thread_id, max(sr) max_sr
FROM records
GROUP BY thread_id
) b ON a.thread_id = b.thread_id AND
a.sr = b.max_sr
WHERE a.action = 'MyAction'
You can use SELF JOIN, but it is not advisable and will impact your query performance. Please check below query for your reference
SELECT DISTINCT r1.thread_id, MAX(r2.thread_no) from records r1 LEFT JOIN records r2 ON r2.thread_id=r1.thread_id WHERE r1.client_name='MyClient' AND r2.action='Reviewed'
SELECT a.maxthreadid,
b.maxthreadno
FROM (SELECT DISTINCT( thread_id ) AS MaxThreadId
FROM records
WHERE client_name = 'MyClient') a
CROSS JOIN (SELECT Max(thread_no) AS MaxThreadNo
FROM records
WHERE thread_id = 'loop_result_from_above_query'
AND action = 'Reviewed') b
Try this.
SELECT *
FROM (SELECT Row_number()
OVER (
partition BY thread_id
ORDER BY thread_no) no,
Max(thread_no)
OVER(
partition BY thread_id ) Maxthread_no,
thread_id,
action,
client_name
FROM records
Where client_name = 'MyClient') AS T1
WHERE no = 1
AND action = 'Reviewed'