I have a table wp_views, with columns postid and views
I want to get the IDs that have the highest values of views (top 4)
Then return the title and link from wp_posts using the postid.
What's the right way of doing this?
You can try the following
global $wpdb;
$top4=$wpdb->get_results('SELECT post_title, post_name from `'.$wpdb->prefix.'views`
INNER JOIN `'.$wpdb->prefix.'posts` ON `postid`=`ID`
ORDER BY `views` DESC
LIMIT 4;', ARRAY_A);
I have tried to replicate your table structure from what your write and from this i have come up with the following:
SELECT id, title, link
FROM wp_views RIGHT JOIN wp_posts ON wp_posts.id = wp_views.post_id
ORDER BY views DESC
LIMIT 4;
you can try it out here: http://sqlfiddle.com/#!9/1cea23/1
I am using RIGHT JOIN to allow null values in the wp_posts part of the result. If you want to avoid NULL values in your results you can use INNER JOIN instead.
Related
I have a query that works perfectly, however I need to change it a bit but it shows me an error and I can't figure out why. Below is the code before and after the changes I made:
BEFORE:
SELECT *,
(SELECT GROUP_CONCAT(pho_file_name) FROM post_images WHERE pho_post_id=posts.ID) AS photo_file_array
FROM users
INNER JOIN posts ON users.Id = posts.post_author
ORDER BY posts.ID;
AFTER:
SELECT *,
(SELECT GROUP_CONCAT(pho_file_name) FROM post_images WHERE pho_post_id=posts.ID) AS photo_file_array
FROM users WHERE users.Id = "1"
INNER JOIN posts ON users.Id = posts.post_author ON posts.post_date = "2020-12-04 07:51:21"
ORDER BY posts.ID;
It shows me the following error:
#1064 - You have an error in your SQL syntax; check the manual that corresponds to your MariaDB server version for the right syntax to use near 'INNER JOIN posts ON users.Id = posts.post_author AND posts.post_date "2020-12...' at line 4
I'm a newbie on MySql but from what I can understand I think the error occurs because of the the double ON inside the INNER JOIN. So, is it possible to add multiple ON inside the INNER JOIN? Thanks in advance!!
You have a few syntax issues, you can't put joins and where anywhere, you also need to use the correct delimiters and data types.
Try the following and note using table and column aliases makes for an easier-to-read query.
Additionally, consider not using select * and reference only the columns you actually require, if possible.
SELECT u.*, p.*, (
SELECT GROUP_CONCAT(i.pho_file_name)
FROM post_images i
WHERE i.pho_post_id = p.ID
) AS photo_file_array
FROM users u
JOIN posts p ON p.post_author = u.Id
AND p.post_date = '2020-12-04 07:51:21'
WHERE u.Id = 1
ORDER BY p.ID;
Here is a full working query. The errors (double ONclause, WHERE clause in the wrong position, wrong quotes) are corrected. Moreover, the ID is compared to an integer now and the post_date to a timestamp literal. I've used table aliases to get this more readable.
SELECT
u.*,
p.*,
(
SELECT GROUP_CONCAT(pi.pho_file_name)
FROM post_images pi
WHERE pi.pho_post_id = p.id
) AS photo_file_array
FROM users u
INNER JOIN posts p ON p.post_author = u.id
AND p.post_date = TIMESTAMP '2020-12-04 07:51:21'
WHERE u.id = 1
ORDER BY p.id;
As to the tables: I suggest you are more consistent with your column names. Why do you call the post ID post_author? One would assume a name here. Just call it post_id in every table. And you don't have to precede columns with abreviations like pho. Just qualify all columns with their tables like I did in my query.
Hi I need to Order using count from another table. i found this great example, im using it as model for a query i need. SQL - How To Order Using Count From Another Table
The model im using for query is:
SELECT bloggers.*, COUNT(post_id) AS post_count
FROM bloggers LEFT JOIN blogger_posts
ON bloggers.blogger_id = blogger_posts.blogger_id
GROUP BY bloggers.blogger_id
ORDER BY post_count
But i have a syntax problem in mine, i guess, im trying to replace the next query, with the one that counts another table... but i cant manage to do it. Original query:
$res3=$db->execute_query("select id,scode,sname from ".TABLE_PREFIX."states where ccode=? order by sname asc",array($country));
Trying to replace with this query..
$res3=$db->execute_query("select ".TABLE_PREFIX."states.* , COUNT(".TABLE_PREFIX."items.state) AS state_count FROM ".TABLE_PREFIX."states LEFT JOIN ".TABLE_PREFIX."items ON ".TABLE_PREFIX."states.id = ".TABLE_PREFIX."items.state GROUP BY ".TABLE_PREFIX."states.id ORDER BY state_count DESC",array($country));
Try this:
$res3=$db->execute_query("select a.* , COUNT(b.state) AS state_count FROM states a
LEFT JOIN items b ON a.id = b.state
GROUP BY a.id
ORDER BY state_count DESC",array($country));
Initially I need to build a query fetching sites from one table ordered by date of newest article (articles placed in the separate table).
I build the following query:
SELECT *
FROM `sites`
INNER JOIN `articles` ON `articles`.`site_id` = `sites`.`id`
ORDER BY `articles`.`date` DESC
GROUP BY `sites`.`id`
I supposed that SELECT and INNER JOIN will fetch all posts and associate a site to each one, than ORDER BY will order the result by descending of post date than GROUP BY will take the very first post for each site and I will get the needed result.
But I'm receiving MySQL error #1064 - You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'GROUP BYsites.idLIMIT 0, 30' at line 7
If I place GROUP BY before ORDER BY statement the query is working but it will not give me the newest post for each site. Instead the result will be sorted after the grouping which is not the thing I need (actually I could prefer to order in another way after grouping).
I read several pretty similar questions but they all related to the data stored in a single table making it possible to use MAX and MIN functions.
What should I do to implement what I need?
You can use either a subquery / derived-table / inline-view or a self-exclusion join, e.g.:
SELECT s.*, a1.*
FROM `sites` s
INNER JOIN `articles` a1 ON a1.`site_id` = s.`id`
LEFT OUTER JOIN `articles` a2 ON a2.`site_id` = a1.`site_id`
AND a2.`date` > a1.`date`
WHERE
a2.`site_id` IS NULL
ORDER BY
a1.`date` DESC
The principle is that you select the sites for which there is no article date greater than any other article date.
rewrite the sql to the following syntax -
SELECT `articles`.`article_name`,'sites'.'id','articles'.'site_id'
FROM `sites`,'articles'
WHERE `articles`.`site_id` = `sites`.`id`
ORDER BY 'sites'.'id', `articles`.`date` DESC;
Do something like this in the select statement. Group by function demands that all fields to be grouped. Hence usage of * is not possible.
SELECT * FROM ( SELECT `S.<col1>`, `S.<col2>`, `A.<col1>`,`A.<col2>`,
ROW_NUMBER ()
OVER (PARTITION BY `SITES`.`ID`
ORDER BY `SITES`.`ID` DESC)
RID
FROM `SITES` `S`,`ARTICLES` `A`
WHERE `ARTICLES`.`SITE_ID` = `SITES`.`ID`
)
WHERE RID = 1;
Can you try this?
Finally I came to the solution.
First of all I changed the main query from queering from sites table to queering from articles. Next I added the MAX(date) column to the result.
So the resulting query implementing the thing I need is the following:
SELECT `sites`.`url`,MAX(`articles`.`date`) AS `last_article_date`
FROM `articles`
INNER JOIN `sites` ON `sites`.`id` = `article`.`site_id`
GROUP BY `site_id`
ORDER BY `last_article_date` ASC
Thanks to all of you for giving me hints and right search directions!
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
I need to find the latest post for each author and then group the results so I only a single latest post for each author.
SELECT wp_posts.* FROM wp_posts
WHERE wp_posts.post_status='publish'
AND wp_posts.post_type='post'
GROUP BY wp_posts.post_author
ORDER BY wp_posts.post_date DESC
This is correctly grouping the output so I only get one post per author, but it is ordering the results after they have been grouped and not before they have been selected.
select wp_posts.* from wp_posts
where wp_posts.post_status='publish'and wp_posts.post_type='post'
group by wp_posts.post_author
having wp_posts.post_date = MAX(wp_posts.post_date) /* ONLY THE LAST POST FOR EACH AUTHOR */
order by wp_posts.post_date desc
EDIT:
After some comments I have decided to add some additional informations.
The company I am working at also uses Postgres and especially SQL Server. This databases don't allow such queries. So I know that there is a other way to do this (I write a solution below). You shoud also have to know what you do if you don't group by all columns treated in the projection or use aggregate functions. Otherwise let it be!
I chose the solution above, because it's a specific question. Tom want to get the recent post for each author in a wordpress site. In my mind it is negligible for the analysis if a author do more than one post per second. Wordpress should even forbid it by its spam-double-post detection. I know from personal experience that there is a really significant benefit in performance doing a such dirty group by with MySQL. But if you know what you do, then you can do it! I have such dirty groups in apps where I'm professionally accountable for. Here I have tables with some mio rows which need 5-15s instead of 100++ seconds.
May be useful about some pros and cons: http://ftp.nchu.edu.tw/MySQL/tech-resources/articles/debunking-group-by-myths.html
SELECT
wp_posts.*
FROM
wp_posts
JOIN
(
SELECT
g.post_author
MAX(g.post_date) AS post_date
FROM wp_posts as g
WHERE
g.post_status='publish'
AND g.post_type='post'
GROUP BY g.post_author
) as t
ON wp_posts.post_author = t.post_author AND wp_posts.post_date = t.post_date
ORDER BY wp_posts.post_date
But if here is more then one post per second for a author you will get more then one row and not the only last one.
Now you can spin the wheel again and get the post with the highest Id. Even here it is at least not guaranteed that you really get the last one.
Not sure if I understand your requirement correct but following inner statement gets the list of the latest post_date for each author and joins these back with the wp_posts table to get a complete record.
SELECT *
FROM wp_posts wp
INNER JOIN (
SELECT post_author
, MAX(post_date) AS post_date
FROM wp_posts
WHERE post_status = 'publish'
AND post_type = 'post'
GROUP BY
post.author
) wpmax ON wpmax.post_author = wp.post_author
AND wpmax.post_date = wp.post_date
ORDER BY
wp.post_date DESC
I think that #edze response is wrong.
In the MySQL manual you can read:
MySQL extends the use of GROUP BY so that the select list can refer to
nonaggregated columns not named in the GROUP BY clause. You can use
this feature to get better performance by avoiding unnecessary column
sorting and grouping. However, this is useful primarily when all
values in each nonaggregated column not named in the GROUP BY are the
same for each group. The server is free to choose any value from each
group, so unless they are the same, the values chosen are
indeterminate. Furthermore, the selection of values from each group
cannot be influenced by adding an ORDER BY clause. Sorting of the
result set occurs after values have been chosen, and ORDER BY does
not affect which values the server chooses.
Two great references:
http://kristiannielsen.livejournal.com/6745.html
http://www.xaprb.com/blog/2006/12/07/how-to-select-the-firstleastmax-row-per-group-in-sql/
Sorry, but I can not comment the #edze response because of my reputation, so I have written a new answer.
Do a GROUP BY after the ORDER BY by wrapping your query with the GROUP BY like this:
SELECT t.* FROM (SELECT * FROM table ORDER BY time DESC) t GROUP BY t.author
it doesn't matter if you order before or after the group-statement, because order means only that 213 goes to 123 or 321 and not more. group by takes only SOME entry per column, not only the latest. I consider you working with subselects here like
SELECT wp_posts.* FROM wp_posts
WHERE wp_posts.post_status='publish'
AND wp_posts.post_type='post'
AND wp_posts.post_date = (Select max(post_date) from wp_posts where author = ... )
What do you think about this?? Seems to work for me
SELECT wp_posts.post_author, MAX(wp_posts.post_date), wp_posts.status, wp_posts.post_type
FROM wp_posts
WHERE wp_posts.post_status='publish'
AND wp_posts.post_type='post'
GROUP BY wp_posts.post_author
It brings me all the Authors with the most updated post_date ... Do you identify a problem there?? I don't
SELECT wp_posts.*,max(wp_posts.post_date) FROM wp_posts
WHERE wp_posts.post_status='publish'
AND wp_posts.post_type='post'
GROUP BY wp_posts.post_author
When our table became large, performance need to checked also.
I checked all the options in the questions here, with a PM system with a 136K messages and link table with 83K rows.
When you need only count, or only IDs - Alex's solution is the best.
SELECT wp_posts.post_author, MAX(wp_posts.post_date), wp_posts.status, wp_posts.post_type
FROM wp_posts
WHERE wp_posts.post_status='publish'
AND wp_posts.post_type='post'
GROUP BY wp_posts.post_author
When you need other fields, I need to modify Husky110 solution (to my table design - here it is only example - not checked), that in my tables 10x faster than the subquery option:
SELECT wp_posts.* FROM wp_posts,
(Select post_id as pid, max(post_date) maxdate from wp_posts where author = ... group by author order by maxdate desc limit 4) t
WHERE wp_posts.post_status='publish'
AND wp_posts.post_type='post'
AND wp_posts.post_id = pid
This change can select more than one post (one for user, for example), and can be modified to other solutions.
Moshe.
Use the below code...
<?php
//get all users, iterate through users, query for one post for the user,
//if there is a post then display the post title, author, content info
$blogusers = get_users_of_blog();
if ($blogusers) {
foreach ($blogusers as $bloguser) {
$args = array(
'author' => $bloguser->user_id,
'showposts' => 1,
'caller_get_posts' => 1
);
$my_query = new WP_Query($args);
if( $my_query->have_posts() ) {
// $user = get_userdata($bloguser->user_id);
// echo 'This is one post for author with User ID: ' . $user->ID . ' ' . $user- >user_firstname . ' ' . $user->user_lastname;
while ($my_query->have_posts()) : $my_query->the_post(); ?>
<?php the_title(); ?>
<small><?php the_time('F jS, Y') ?> by <?php the_author_posts_link() ?> </small><?php
the_content();
endwhile;
}
}
}
?>
HERE a simple answer from
http://www.cafewebmaster.com/mysql-order-sort-group
SELECT * FROM
(
select * from `my_table` order by timestamp desc
) as my_table_tmp
GROUP BY catid
ORDER BY nid desc
it worked wonders for me