I have been struggling with this problem for about month..
Have been searching and reading many posts, but still can't figure out, how to make this work..
Basically: I got 2 database tables fun_posts and fun_post_upvotes And I want to
SELECT *
FROM fun_posts
ORDER BY (HOTTEST POSTS(MOST UPVOTED THIS WEEK))
This is my latest code, that won't work
SELECT *
FROM fun_posts
ORDER BY (SELECT count(*), image_id, date
FROM fun_post_upvotes
GROUP BY image_id
ORDER BY DATE(date) > (NOW() - INTERVAL 7 DAY) DESC,
count(*) DESC,
date DESC)
If I divide this line into 2 different SELECT functions, they work. I can select simple posts and I can select upvotes count ordered like I want.
But If I make them into one line like that, I get following error:
#1241 - Operand should contain 1 column(s)
EDIT NR 1:
fun_posts table
fun_post_upvotes table
Problem with Answer that I checked:
Here, look how posts are ordered in my select function. (It selects like I want) 10->134->132->2->13
And here with given code (It selects image, but not in that order) 10->122->39->8->110
You can use a join to do this
SELECT fp.*, fpu.`cnt`
FROM fun_posts fp
LEFT JOIN ( SELECT image_id, COUNT(*) AS cnt
FROM fun_post_upvotes
WHERE `date` > (NOW() - INTERVAL 7 day)
GROUP BY image_id
) fpu ON ( fpu.image_id = fp.id )
ORDER BY fpu.cnt DESC, fp.`date` DESC, fp.`id` DESC;
It selects a list from fun_post_upvotes grouped by image_id and counts the amount of rows. That list is returned to the main query and matches (LEFT JOIN) on fp.id. The query will first show the item with the most upvotes in the past 7 days, than the least. If no upvotes are found, the result will still return them, but at the bottom in no specific order.
You can edit the order by, to obtain the items in the order you like.
Here a sqlfiddle.com
Related
I have a series of news articles, that are stored inside a database, like so:
id
articleTitle
articleBody
articleBy
category
dateEntered
What I want to do is select all of the articles and group them by a particular month / year that they were entered. For example:
May
News article 1
News article 2
News article 3
Feb
News article 4
News article 5
News article 6
I am able to select the months, as well as how many items are there, using the following:
SELECT id, articleTitle, YEAR(dateEntered) AS 'year', MONTH(dateEntered) AS 'month' FROM News GROUP BY YEAR(dateEntered), MONTH(dateEntered) DESC
Whenever I try to output the contents of 'articleTitle' it only shows 1 result, when there should be 28 entries that are showing.
Where am I going wrong in my query?
The GROUP BY clause collapses sets of rows with common values for the expressions in the GROUP BY clause. With this in your query:
GROUP BY YEAR(dateEntered), MONTH(dateEntered)
The query will only return a single row for distinct values of those expressions. There is nothing wrong with doing this. This is convenient if you want to return a count of the number of rows that have that year and month, for example
SELECT DATE_FORMAT(dateEntered,'%Y-%m')
, COUNT(1) AS cnt_
FROM mytable
GROUP BY DATE_FORMAT(dateEntered,'%Y-%m')
If you don't want your query to "collapse" the rows, then don't use a GROUP BY clause.
I suspect you want to use an ORDER BY clause, not a GROUP BY. To make the order the rows are returned in more deterministic, you can add more expressions to the ORDER BY clause. Also note that ASC and DESC apply to each expression in the ORDER BY clause.
For example:
SELECT n.id
, n.articleTitle
, YEAR(n.dateEntered) AS `year`
, MONTH(n.dateEntered) AS 'month'
FROM News n
ORDER
BY YEAR(n.dateEntered) DESC
, MONTH(n.dateEntered) DESC
, n.id DESC
So basically I'm getting notifications of new content on my website. I have 4 tables -
articles
media
updates
comments
Each table has a set of its own columns (I can include these if anyone wants). There is one distinct column every table has, this is the timestamp column (a big int formatted column with data from the PHP time() function). My solution to getting the last 30 modifications is to select the first 30 rows from these 4 tables ordered by timestamp descending.
Here is the query I have so far, it doesn't work and I'm wondering if someone could help me. -
SELECT * FROM `articles`
UNION SELECT * FROM `media`
UNION SELECT * FROM `updates`
UNION SELECT * FROM `comments`
ORDER BY `timestamp` DESC
LIMIT 30
EDIT:
I was also using another query before -
SELECT * FROM `articles` ,`media` ,`updates` ,`comments`
ORDER BY `timestamp` DESC
LIMIT 30
and kept getting this error -
Column 'timestamp' in order clause is ambiguous
EDIT 2
I realise now I have to use the AS clause in my statement to combine these results into one table.
SELECT a.*,m.*,u.*,c.* from articles AS a
LEFT JOIN media AS m ON (m.timestamp = a.timestamp)
LEFT JOIN updates AS u ON (u.timestamp = a.timestamp)
LEFT JOIN comments AS c ON (c.timestamp = a.timestamp)
ORDER BY timestamp desc LIMIT 30
Your union can work, but only if you can create some sort of common field list. For example, lets say you have a description field in each table, with different names. Something like this will work...
SELECT TimeStamp,'Articles',Art_desc AS Description FROM articles
UNION ALL
SELECT TimeStamp,'Media',Media_Desc FROM Media
UNION ALL
SELECT TimeStamp,'Updates',Update_Desc FROM Updates
UNION ALL
SELECT TimeStamp,'Comments',Comment FROM Comments
ORDER BY timeStamp DESC LIMIT 30
In essence, you are creating result sets of 3 consistent columns, so UNION will work in this case.
In one table I have
ID, PAGE_ID, DATE
Each time a page is loaded, the DATE, PAGE_ID [from the page table below] are loaded into the table above.
I am trying to calculate and sort pages by popularity. The page table contains:
ID [PAGE_ID], DESCRIPTION, DATE
I have no idea where to start.
select L.PAGE_ID, P.DESCRIPTION, count(L.ID) from LOADED_PAGE L
inner join PAGE P on P.ID = L.PAGE_ID
where L.DATE > :sevenDaysAgo
group by L.PAGE_ID, P.DESCRIPTION
order by count(L.ID) desc
will give you the list of loaded pages, from the most popular to the least one.
select
id_page,
count(*) as popularity
from table
where date >= curdate() - interval 7 day
group by id_page
order by popularity desc
I'm kind of new to SQL and I can't find the solution to my problem. I have two tables. In table A, I'm storing a lot of comments, each with a unique ID.
In table B, I'm storing every vote (like=1 and dislike=0) for every comment with a datetime. There will be an entry for every vote, so there will be tons of rows for each comment in table A.
I need to retrieve all the comments and sort them such that the weekly most liked comments are at the top, but I'm not sure how.
Here's what I have so far, but not sure how to continue:
SELECT * FROM comment INNER JOIN logs ON comment.c_id=logs.c_id WHERE logs.daterate >= DATE_SUB(CURDATE(), INTERVAL 8 DAY) AND logs.rated=1
To clarify, I need to get all entries from logs with rated = 1 in the past week and sort them by the most frequent c_id in descending order, and get distinct c_id for each row... if that makes sense
Please ask questions if I didn't make it clear enough, thanks!!
SELECT *
FROM comment
INNER JOIN (SELECT comment.c_id,
COUNT(*) AS cnt
FROM comment
INNER JOIN logs ON comment.c_id=logs.c_id
WHERE logs.daterate >= DATE_SUB(CURDATE(), INTERVAL 8 DAY)
AND logs.rated=1
GROUP BY comment.c_id) x ON x.c_id = comment.c_id
ORDER BY x.cnt DESC
Try this -
I have first queried all records from logs table which are rated 1 and are from 7 days from current date and also are ordered based on the count of c_id. Then joined this with the COmments table.
SELECT Comment.* FROM comment C
INNER JOIN (SELECT logs.c_id as c_id,count(logs.c_id) as logcount FROM logs
WHERE logs.rated=1
AND logs.daterate BETWEEN GETDATE() AND DATEADD(day,-7,getdate())
Group by logs.c_id
order by count(logs.c_id) desc) X
ON C.c_id = X.c_id
ORDER BY X.logcount DESC
I am working on an auction web application. Now i have a table with bids, and from this table i want to select the last 10 bids per auction.
Now I know I can get the last bid by using something like:
SELECT bids.id FROM bids WHERE * GROUP BY bids.id ORDER BY bids.created
Now I have read that setting an amount for the GROUP BY results is not an easy thing to do, actually I have found no easy solution, if there is i would like to hear that.
But i have come up with some solutions to tackle this problem, but I am not sure if i am doing this well.
Alternative
The first thing is creating a new table, calling this bids_history. In this table i store a string of the last items.
example:
bids_history
================================================================
auction_id bid_id bidders times
1 20,25,40 user1,user2,user1 time1,time2,time3
I have to store the names and the times too, because I have found no easy way of taking the string used in bid_id(20,25,40), and just using this in a join.
This way i can just just join on auction id, and i have the latest result.
Now when there is placed a new bid, these are the steps:
insert bid into bids get the lastinserteid
get the bids_history string for this
auction product
explode the string
insert new values
check if there are more than 3
implode the array, and insert the string again
This all seems to me not a very well solution.
I really don't know which way to go. Please keep in mind this is a website with a lot of bidding's, they can g up to 15.000 bidding's per auction item. Maybe because of this amount is GROUPING and ORDERING not a good way to go. Please correct me if I am wrong.
After the auction is over i do clean up the bids table, removing all the bids, and store them in a separate table.
Can someone please help me tackle this problem!
And if you have been, thanks for reading..
EDIT
The tables i use are:
bids
======================
id (prim_key)
aid (auction id)
uid (user id)
cbid (current bid)
created (time created)
======================
auction_products
====================
id (prim_key)
pid (product id)
closetime (time the auction closses)
What i want as the result of the query:
result
===============================================
auction_products.id bids.uid bids.created
2 6 time1
2 8 time2
2 10 time3
5 3 time1
5 4 time2
5 9 time3
7 3 time1
7 2 time2
7 1 time3
So that is per auction the latest bids, to choose by number, 3 or 10
Using user variable, and control flow, i end up with that (just replace the <=3 with <=10 if you want the ten auctions) :
SELECT a.*
FROM
(SELECT aid, uid, created FROM bids ORDER BY aid, created DESC) a,
(SELECT #prev:=-1, #count:=1) b
WHERE
CASE WHEN #prev<>a.aid THEN
CASE WHEN #prev:=a.aid THEN
#count:=1
END
ELSE
#count:=#count+1
END <= 3
Why do this in one query?
$sql = "SELECT id FROM auctions ORDER BY created DESC LIMIT 10";
$auctions = array();
while($row = mysql_fetch_assoc(mysql_query($sql)))
$auctions[] = $row['id'];
$auctions = implode(', ', $auctions);
$sql = "SELECT id FROM bids WHERE auction_id IN ($auctions) ORDER BY created LIMIT 10";
// ...
You should obviously handle the case where, e.g. $auctions is empty, but I think this should work.
EDIT: This is wrong :-)
You will need to use a subquery:
SELECT bids1.id
FROM ( SELECT *
FROM bids AS bids1 LEFT JOIN
bids AS bids2 ON bids1.created < bids2.created
AND bids1.AuctionId = bids2.AuctionId
WHERE bid2.id IS NULL)
ORDER BY bids.created DESC
LIMIT 10
So the subquery performs a left join from bids to itself, pairing each record with all records that have the same auctionId and and a created date that is after its own created date. For the most recent record, there will be no other record with a greater created date, and so that record would not be included in the join, but since we use a Left join, it will be included, with all the bids2 fields being null, hence the WHERE bid2.id IS NULL statement.
So the sub query has one row per auction, contianing the data from the most recent bid. Then simply select off the top ten using orderby and limit.
If your database engine doesn't support subqueries, you can use a view just as well.
Ok, this one should work:
SELECT bids1.id
FROM bids AS bids1 LEFT JOIN
bids AS bids2 ON bids1.created < bids2.created
AND bids1.AuctionId = bids2.AuctionId
GROUP BY bids1.auctionId, bids1.created
HAVING COUNT(bids2.created) < 9
So, like before, left join bids with itself so we can compare each bid with all the others. Then, group it first by auction (we want the last ten bids per auction) and then by created. Because the left join pairs each bid with all previous bids, we can then count the number of bids2.created per group, which will give us the number of bids occurring before that bid. If this count is < 9 (because the first will have count == 0, it is zero indexed) it is one of the ten most recent bids, and we want to select it.
To select last 10 bids for a given auction, just create a normalized bids table (1 record per bid) and issue this query:
SELECT bids.id
FROM bids
WHERE auction = ?
ORDER BY
bids.created DESC
LIMIT 10
To select last 10 bids per multiple auctions, use this:
SELECT bo.*
FROM (
SELECT a.id,
COALESCE(
(
SELECT bi.created
FROM bids bi
WHERE bi.auction = a.id
ORDER BY
bi.auction DESC, bi.created DESC, bi.id DESC
LIMIT 1 OFFSET 9
), '01.01.1900'
) AS mcreated
COALESCE(
(
SELECT bi.id
FROM bids bi
WHERE bi.auction = a.id
ORDER BY
bi.auction DESC, bi.created DESC, bi.id DESC
LIMIT 1 OFFSET 9
), 0)
AS mid
FROM auctions a
) q
JOIN bids bo
ON bo.auction >= q.auction
AND bo.auction <= q.auction
AND (bo.created, bo.id) >= (q.mcreated, q.mid)
Create a composite index on bids (auction, created, id) for this to work fast.