I have this basic query that returns a main row of a program title(eventdesc) and then lists program participants and info as multiple sub rows.
PROGRAM 1
Email 1, email 2, name, status (first participant)
Email 1, email 2, name, status (second participant)
PROGRAM 2
Email 1, Email 2, name, status (first participant)
ETC...
Basic query:
$query_perpage = "SELECT COUNT(*) FROM camps_events";
$result = mysql_query($query_perpage, $db) or die(mysql_error());
$r = mysql_fetch_row($result);
$numrows = $r[0];
$pages = new Paginator($query);
$pages->items_total = $numrows;
$pages->paginate();
$pages->mid_range = 7;
$query = mysql_query("SELECT ce.eventcode, ce.eventdesc, ce.date, r.participant_fname, r.participant_lname,
r.position, r.dob, r.status, r.email_primary, r.order_number
FROM camps_events ce
RIGHT JOIN registrations r on r.eventcode = ce.eventcode
WHERE ce.reg_status = 'Active'
AND r.status NOT IN ('Incomplete','Canceled')".getAllowedPrograms()."
ORDER BY ce.eventdesc, ce.eventcode, r.participant_lname ASC $pages->limit ") or die(mysql_error());
I've been trying to figure out how to paginate it by Program, no matter how many subrows.
I have a pagination class in place on another page, but that only pulls from one table.
I've been trying to implement the same pagination, but I can only get it to pull the first program, and then it limits the page based on the sub rows, not the main program row. And in the state I've posted it here, each following page displays only the first programs. The sub rows that come up are different on each page, but I can't tell if they are all in the first program.
The query works fine for pulling all results properly, but if it's a huge list, it's extremely inefficient, and can even timeout the browser.
Any help would be much appreciated, please let me know if I can include anything else.
I'm not too concerned with using the same pagination class, so I'm completely open to different approaches.
Thanks in advance
Try using a subselect:
SELECT ce.eventcode, ce.eventdesc, ce.date, r.participant_fname, r.participant_lname,
r.position, r.dob, r.status, r.email_primary, r.order_number
FROM camps_events ce
RIGHT JOIN registrations r on r.eventcode = ce.eventcode
WHERE ce.reg_status = 'Active'
AND r.status NOT IN ('Incomplete','Canceled')".getAllowedPrograms()."
AND ce.id in (select id from camps_events pgce order by ce.eventdesc, ce.eventcode $pages->limit)
ORDER BY ce.eventdesc, ce.eventcode, r.participant_lname ASC ")
or die(mysql_error());
Edit: unfortunately MySQL can not yet limit subqueries. :-(
So it has to be a temp-table:
mysql_query("drop temporary table if exists tmp_events", $db);
mysql_query("create temporary table tmp_events select id from camps_events order by eventdesc, eventcode " . $pages->limit, $db);
mysql_query("SELECT ce.eventcode, ce.eventdesc, ce.date, r.participant_fname, r.participant_lname,
r.position, r.dob, r.status, r.email_primary, r.order_number
FROM camps_events ce
inner join tmp_events pgce on pgce.id = ce.id
RIGHT JOIN registrations r on r.eventcode = ce.eventcode
WHERE ce.reg_status = 'Active'
AND r.status NOT IN ('Incomplete','Canceled')".getAllowedPrograms()."
ORDER BY ce.eventdesc, ce.eventcode, r.participant_lname ASC ")
or die(mysql_error());
There can be of course pages with less than paged items, because events without registrations will not show.
Related
I have 2 tables - users and articles.
users:
user_id (int)
name (varchar)
articles:
article_id (int)
user_id (int)
title (varchar)
description (text)
In my application I need to display 20 RANDOM articles on a page.
My query is like this:
SELECT a.title
, a.description
, u.name
FROM articles a
JOIN users u
USING (user_id)
ORDER
BY RAND()
LIMIT 20
A user can have any number of articles in the database.
Now the problem is sometimes out of 20 results, there are like 9-10 articles from one single user.
I want those 20 records on the page to not contain more than 3 (or say 4) articles from a particular user.
Can I achieve this through SQL query. I am using PHP and MySQL.
Thanks for your help.
You could try this?
SELECT * FROM
(
SELECT B.* FROM
(
SELECT A.*, ROW_NUMBER() OVER (PARTITION BY A.USER_ID ORDER BY A.R) USER_ROW_NUMBER
FROM
(
SELECT a.title, a.description, u.name, RND() r FROM articles a
INNER JOIN users u USING (user_id)
) A
) B
WHERE B.USER_ROW_NUMBER<=4
) C
ORDER BY RAND() LIMIT 20
Mmm, intresting I don't think this is possible through a pure sql query.
My best idea would be to have an array of the articles that you'll eventually display query the database and use the standard SELECT * FROM Articles ORDER BY RAND() LIMIT 20
The go through them, making sure that you have indeed got 20 articles and no one has breached the rules of 3/4 per user.
Have another array of users to exclude, perhaps using their user id as an index and value of a count.
As you go through add them to your final array, if you find any user that hits you rule add them to the array.
Keep running the random query, excluding users and articles until you hit your desired amount.
Let me try some code (it's been a while since I did php)
$finalArray = [];
$userArray = [];
while(count($finalArray) < 20) {
$query = "SELECT * FROM Articles ";
if(count($finalArray) > 0) {
$query = $query . " WHERE articleID NOT IN(".$finalArray.")";
$query = $query . " AND userID NOT IN (".$userArray.filter(>4).")";
}
$query = $query . " ORDER BY Rand()";
$result = mysql_query($query);
foreach($row = mysql_fetch_array($result)) {
if(in_array($finalArray,$row) == false) {
$finalArray[] = $row;
}
if(in_array($userArray,$row[userId]) == false) {
$userArray[$row[userId]] = 1;
}
else {
$userArray[$row[userId]] = $userArray[$row[userId]] + 1;
}
}
The system works but I am sure there is another way of coding this in order to make it easier to access the users level depending on their XP points.
$getxp = mysql_query("SELECT `xp` FROM `members` WHERE `id` = '$logged[id]'");
$xp = mysql_fetch_array($getxp);
$x = $xp['xp'];
echo "$x";
$level = MYSQL_QUERY("SELECT * FROM `levels` WHERE `xp` >= '$x' LIMIT 1");
while ($n = mysql_fetch_array($level)) {
$mylvl = $n[level];
echo "You are a level $mylvl";
}
I have a database table for 'MEMBERS' (ID, USERNAME, PASS, XP) and a table for 'LEVELS' (ID, XP, LEVELS). Let me know of an easier method to get the LVL for the user. Many Thanks!
I think this should do it.
SELECT `levels`
FROM `members` m
LEFT JOIN `levels` l ON m.`xp` >= l.`xp`
WHERE m.`id` = '. $logged[id] .'
ORDER BY `levels` ASC
LIMIT 1;
Get all members where your member.id = $logged[id]. Next, link your member.id to all xp-requirements that are smaller than your current exp. This will give you a list of all the levels that you surpassed. Now the only thing you have to do is order them in a way that the highest level is first, and then simply limit it to 1 entry. This should result in the highest level that your exp allows you to have -- therefore your current level.
Note that of course, the more levels you have, the larger the LEFT JOIN becomes, which will end up consuming more memory on your SQL server.
also note you're using MYSQL. This is outdate and will be taken out of the next PHP version. Look into MYSQLi at least, or go straight for PDO. This way you wont have to change all your code once the new PHP releases.
$sql = "SELECT * FROM levels WHERE xp >= (SELECT xp FROM members WHERE id='".$loggedin['id']."')";
subselect not a join as you have no keys relating levels to members
Here is my code:
<?php
$data = mysql_query("SELECT * FROM board") or die(mysql_error());
while($info = mysql_fetch_assoc( $data ))
{
if(!empty($info['user'])){
Print "".$info['user'].""; }
else {
}
myOtherQuery($info['id']);
}
function myOtherQuery($id) {
$result3 = mysql_query("SELECT COUNT(source_user_id) FROM likes
INNER JOIN pins ON pins.id = likes.pin_id
WHERE pins.board_id='$id'");
$c = mysql_result($result3, 0); // Cumulative tally of likes for board
{
Print "$c";
}
}
?>
The first part gets a users name and board details (board as in a photo album).
the second part joins that data with another sql table that counts the number of likes that board has.
Both are displayed as a name and a score represented by a number.
By default they are ordered by the date of creation. I'd like to be able to order them by the score. However, since the score is determined in the second part of the code, I don't know how to achieve it. Is it possible?
The solution is of course to query both at once in the first place, via a LEFT JOIN against a subquery returning the count per board_id:
SELECT
board.*,
/* Your PHP code will retrieve the likes count via this alias `numlikes` as in $info['numlikes'] */
numlikes
FROM
board
LEFT JOIN (
/* Subquery returns count per board_id */
SELECT pins.board_id, COUNT(source_user_id) AS numlikes
FROM
likes
INNER JOIN pins ON pins.id = likes.pin_id
GROUP BY pins.board_id
) likes ON board.id = likes.board_id
ORDER BY numlikes
It is nearly always significantly more efficient to perform a single query rather than n queries in a loop. You should strive to do so whenever possible.
You can do it in one query
SELECT board.*, count(likes.source_user_id) as score
FROM board
INNER JOIN pins
ON pins.board_id = board.id
INNER JOIN likes
ON pins.id = likes.pin_id
ORDER BY score
i have a online application for wich i require a sort of dashboard (to use the white-space).
There are three tables used for the operation:
1.) categories: id, name
2.) entries: id, name, description, category_id, created, modified
3.) entryimages: id, filename, description, entry_id
on the dashboard i want to show 4-5 entries (with thumbnail images, so i require joins to the entryimages table and the categories table) for each category.
I read through some articles (and threads on s.o.) like this one:
http://www.xaprb.com/blog/2006/12/07/how-to-select-the-firstleastmax-row-per-group-in-sql/
But am still not getting it right, i've tried to first extract all categories and for each and every category build a query and with "all union" attach them to one, but that is not working.
The last version of code i used:
foreach($categories as $id => $name)
{
$query .= "SELECT `entry`.`id`,
`entry`.`name`,
`entry`.`description`,
`entry`.`category_id`,
`entry`.`created`,
`entry`.`modified`,
`entryimages`.`filename`,
`entryimages`.`description`
FROM `entries` as `entry` LEFT JOIN `entryimages` ON `entryimages`.`entry_id` = `entry`.`id`
WHERE `entry`.`category_id` = $id ";
if($i < count($groups))
{
$query .= 'UNION ALL ';
}
$i++;
}
$result = mysql_query($query);
Does anybody know what is the best right to accomplish this operation?
Thanks 1000
On the dashboard if you want to show three entries, the way you are doing is wrong. If my understanding is right, the entire query will be something like
"SELECT `entry`.`id`,
`entry`.`name`,
`entry`.`description`,
`entry`.`category_id`,
`entry`.`created`,
`entry`.`modified`,
`entryimages`.`filename`,
`entryimages`.`description`
FROM `entries` as `entry`
INNER JOIN categories
ON (entry.category_id = categories.id)
LEFT JOIN (SELECT * FROM `entryimages` WHERE `entry_id` = `entry`.`id` LIMIT 1) AS `entryimages`
ON `entryimages`.`entry_id` =`entry`.`id`
ORDER BY `entry`.`created` DESC LIMIT 5";
Your code looks ok to me you should just add a LIMIT clause so that you get just five of them and an ORDER BY clause to get the latest
$query .= "SELECT `entry`.`id`,
`entry`.`name`,
`entry`.`description`,
`entry`.`category_id`,
`entry`.`created`,
`entry`.`modified`,
`entryimages`.`filename`,
`entryimages`.`description`
FROM `entries` as `entry` LEFT JOIN `entryimages` ON `entryimages`.`entry_id` = `entry`.`id`
WHERE `entry`.`category_id` = $id ORDER BY `entry`.`created` DESC LIMIT 5";
I want multiple photos and multiple videos, the main problem is that I can't get them inline if I don't use joins.
So for example, I get 2 photos a video and again a photo.
I have a parent news table and 2 secondary table news_photos and news_videos and I want to get in one query the photos and videos for the news.
Is this somehow possible?
mysql_query("
SELECT *
FROM news_photos, news_videos
FULL JOIN news_videos
ON news_id = {$news_id}
FULL JOIN news_photos
ON news_id = {$news_id}
");
An image about the structure:
There's actually only a single FULL JOIN in that, since you are not involving the news table at all.
SELECT *
FROM news_photos
FULL JOIN news_videos
ON news_photos.news_id=news_videos.news_id
WHERE news_photos.news_id=... OR news_videos.news_id=...
FULL JOIN is not supported by MySQL. It can be less-efficiently simulated using two LEFT JOINs and a UNION, but it's relatively rare that you actually need to. Assuming every photo and video does belong to a news, you could avoid it and get a more conventional query by bringing the news table into it:
SELECT *
FROM news
LEFT JOIN news_photos ON news_photos.news_id=news.id
LEFT JOIN news_videos ON news_videos.news_id=news.id
WHERE news_id=...
But still, this is almost certainly not what you mean! If there are multiple photos and videos for a news item, you would be effectively creating a cartesian product, where every combination of photo and video produces a row. This is the sort of combinatorial explosion you almost never want!
If you just want one of each photo and video, I suppose you could hack that into a single query using a LEFT JOIN that will always give NULL on the other side:
SELECT * FROM news_photos
LEFT JOIN news_videos ON 0
WHERE news_photos.news_id=...
UNION SELECT * FROM news_photos
RIGHT JOIN news_videos ON 0
WHERE news_videos.news_id=...
But there's really nothing to be gained by this. Don't shoehorn two separate queries (“I'd like the photos for a news, and the videos for a news”) into one. Just do it the trivial way:
SELECT * FROM news_photos
WHERE news_id=...
SELECT * FROM news_videos
WHERE news_id=...
i would do it using a stored procedure that had multiple select statements as follows:
http://pastie.org/1141100
drop procedure if exists list_news_photos_videos;
delimiter #
create procedure list_news_photos_videos
(
in p_news_id int unsigned
)
proc_main:begin
select n.* from news n where n.news_id = p_news_id;
select p.* from news_photos p where p.news_id = p_news_id order by photo_id desc;
select v.* from news_videos v where v.news_id = p_news_id order by video_id desc;
end proc_main #
you would call this in mysql as follows:
call list_news_photos_videos(2);
then you can call the stored procedure from php (1 db call only) using mysqli as follows:
http://pastie.org/1141103
<?php
// quick and dirty demo - needs to be made more robust !!
$db = new Mysqli("localhost", "foo_dbo", "pass", "foo_db");
$sql = sprintf("call list_news_photos_videos(%d)", 2); // get all the news related data in one query
$result = $db->query($sql);
//news item
$row = $result->fetch_assoc();
echo sprintf("<h2>news item</h2>news_id = %d subject = %s <br/>", $row["news_id"], $row["subject"]);
$result->free();
//news photos
$db->next_result();
$result = $db->use_result();
echo "<h2>news photos</h2>";
while ($row = $result->fetch_assoc()){
echo sprintf("photo_id = %d subject = %s<br/>", $row["photo_id"], $row["subject"]);
}
$result->free();
//news videos
$db->next_result();
$result = $db->use_result();
echo "<h2>news videos</h2>";
while ($row = $result->fetch_assoc()){
echo sprintf("video_id = %d subject = %s<br/>", $row["video_id"], $row["subject"]);
}
$result->free();
$db->close();
?>