Related
I have three tables viz. tb_filters, tb_products, and tb_products_to_filters. The structure of these tables along with some dummy data is given by:
tb_filters:
CREATE TABLE IF NOT EXISTS `tb_filters`
(
`filter_id` INT (11) AUTO_INCREMENT PRIMARY KEY,
`filter_name` VARCHAR (255)
);
INSERT INTO `tb_filters`
(`filter_name`)
VALUES ('USB'),
('High Speed'),
('Wireless'),
('Ethernet');
tb_products:
CREATE TABLE IF NOT EXISTS `tb_products`
(
`product_id` INT (11) AUTO_INCREMENT PRIMARY KEY,
`product_name` VARCHAR (255)
);
INSERT INTO `tb_products`
(`product_name`)
VALUES ('Ohm precision shunt resistor'),
('Orchestrator Libraries'),
('5cm scanner connection'),
('Channel isolated digital'),
('Network Interface Module');
tb_products_to_filters:
CREATE TABLE IF NOT EXISTS `tb_products_to_filters`
(
`id` INT (11) AUTO_INCREMENT PRIMARY KEY,
`product_id` INT (11),
`filter_id` INT (11)
);
INSERT INTO `tb_products_to_filters`
(`product_id`, `filter_id`)
VALUES (1, 1),
(2, 2),
(3, 3),
(4, 3),
(1, 3);
By looking into above "tb_products_to_filters" table, my required queries are:
When filter id = 1 and 3 are selected via checkbox on the page, all those products which belong to filter id 1 as well as filter id 3 must be fetched from the database. In this case, the product with id 1 should come.
Second, when only one filter (say id = 3) is checked, then all those products which fall under this id should be fetched. In this condition, the products id 1, 3 and 4 will come.
If filter id 2 is selected, then only one product with id = 2 will come.
If combination of filter (2 and 3) is selected, then no product will come because there is no product which belongs to both of them.
What is the way of writing queries to obtain above goal?
Please note that I want to include columns: product_id, product_name, filter_id and filter_name to display data in table result set.
EDIT:
The output should match below when filter ids 1 and 3 were checked:
EDIT 2:
I'm trying below query to fetch results when filter 1 and 3 were checked:
SELECT `p`.`product_id`, `p`.`product_name`,
GROUP_CONCAT(DISTINCT `f`.`filter_id` ORDER BY `f`.`filter_id` SEPARATOR ', ') AS filter_id, GROUP_CONCAT(DISTINCT `f`.`filter_name` ORDER BY `f`.`filter_name` SEPARATOR ', ') AS filter_name
FROM `tb_products` AS `p` INNER JOIN `tb_products_to_filters` AS `ptf`
ON `p`.`product_id` = `ptf`.`product_id` INNER JOIN `tb_filters` AS `f`
ON `ptf`.`filter_id` = `f`.`filter_id` GROUP BY `p`.`product_id`
HAVING GROUP_CONCAT(DISTINCT `ptf`.`filter_id` SEPARATOR ', ') = ('1,3')
ORDER BY `p`.`product_id`
But unfortunately, it returns an empty set. Why?
You can use the HAVING clause with GROUP_CONCAT :
SELECT t.product_id,tp.product_name,
GROUP_CONCAT(t.filter_id) as filter_id,
GROUP_CONCAT(tb.filter_name) as filter_name
FROM tb_products_to_filters t
INNER JOIN tb_filters tb ON(t.filter_id = tb.filter_id)
INNER JOIN tb_products tp ON(t.product_id = tp.product_id)
WHERE t.filter_id IN(1,3)
GROUP BY t.product_id
HAVING COUNT(distinct t.filter_id) = 2
You can adjust this any way you want. Note that the number of arguments placed inside the IN() should be the same as the COUNT(..) = X
EDIT:
A DISTINCT keyword is required in GROUP_CONCAT while fetching those columns otherwise all the filters would come in the list. I tried it by doing
SELECT t.product_id,tp.product_name,
GROUP_CONCAT(DISTINCT t.filter_id ORDER BY `t`.`filter_id` SEPARATOR ', ') as filter_id,
GROUP_CONCAT(DISTINCT tb.filter_name ORDER BY tb.filter_name SEPARATOR ', ') as filter_name
FROM tb_products_to_filters t
INNER JOIN tb_filters tb ON(t.filter_id = tb.filter_id)
INNER JOIN tb_products tp ON(t.product_id = tp.product_id)
WHERE t.filter_id IN(1,3)
GROUP BY t.product_id
HAVING COUNT(distinct t.filter_id) = 2
But still all the filter names (Ethernet, High Speed, USB, Wireless) are coming in the list. How to list only those filter names whose corresponding filter id (1, 3) are in the string?
I know this is quite complicated, but I sincerely hope someone will check this out.
I made short version (to better understand the problem) and full version (with original SQL)
Short version:
[TABLE A] [TABLE B]
|1|a|b| |1|x
|2|c|d| |1|y
|3| | | |2|z
|5| | | |2|v
|4|w
How can I make MySQL query to get rows like that:
1|a|b|x|y
2|c|d|z|v
2 columns from A and 2 rows from B as columns, only with keys 1 and 2, no empty results
Subquery?
Full version:
I tried to get from Prestashop db in one row:
product id
ean13 code
upc code
feature with id 24
feature with id 25
It's easy to get id_product, ean13 and upc, as it's one row in ps_product table. To get features I used subqueries (JOIN didn't work out).
So, I selected id_product, ean13, upc, (subquery1) as code1, (subquery2) as code2.
Then I needed to throw out empty rows. But couldn't just put code1 or code2 in WHERE.
To make it work I had to put everything in subquery.
This code WORKS, but it is terribly ugly and I bet this should be done differently.
How can I make it BETTER?
SELECT * FROM(
SELECT
p.id_product as idp, p.ean13 as ean13, p.upc as upc, (
SELECT
fvl.value
FROM
`ps_feature_product` fp
LEFT JOIN
`ps_feature_value_lang` fvl ON (fp.id_feature_value = fvl.id_feature_value)
WHERE fp.id_feature = 24 AND fp.id_product = idp
) AS code1, (
SELECT
fvl.value
FROM
`ps_feature_product` fp
LEFT JOIN
`ps_feature_value_lang` fvl ON (fp.id_feature_value = fvl.id_feature_value)
WHERE fp.id_feature = 25 AND fp.id_product = idp
) AS code2,
m.name
FROM
`ps_product` p
LEFT JOIN
`ps_manufacturer` m ON (p.id_manufacturer = m.id_manufacturer)
) mainq
WHERE
ean13 != '' OR upc != '' OR code1 IS NOT NULL OR code2 IS NOT NULL
create table tablea
( id int,
col1 varchar(1),
col2 varchar(1));
create table tableb
( id int,
feature int,
cola varchar(1));
insert into tablea (id, col1, col2)
select 1,'a','b' union
select 2,'c','d' union
select 3,null,null union
select 5,null,null;
insert into tableb (id, feature, cola)
select 1,24,'x' union
select 1,25,'y' union
select 2,24,'z' union
select 2,25,'v' union
select 4,24,'w';
select a.id, a.col1, a.col2, b1.cola b1a, b2.cola b2a
from tablea a
inner join tableb b1 on (b1.id = a.id and b1.feature = 24)
inner join tableb b2 on (b2.id = a.id and b2.feature = 25);
SQLFiddle here.
What you want to do is called a Pivot Query. MySQL has no native support for pivot queries, though other RDBMSen do.
You can simulate a pivot query with derived columns, but you must specify each derived column. That is, it is impossible in MySQL itself to have the number of columns match rows of another table. This has to be known ahead of time.
It would be much easier to query the results as rows and then use PHP to do the aggregation into columns. For example:
while ($row = $result->fetch()) {
if (!isset($table[$row->id])) {
$table[$row->id] = array();
}
$table[$row->id][] = $row->feature;
This is not a simple question because it's not a standard query, by the way if you can make use of views you can do the following procedure. Assuming you're starting from this tables:
CREATE TABLE `A` (
`id` int(11) unsigned NOT NULL AUTO_INCREMENT,
`firstA` char(1) NOT NULL DEFAULT '',
`secondA` char(1) NOT NULL DEFAULT '',
PRIMARY KEY (`id`)
);
CREATE TABLE `B` (
`id` int(11) unsigned NOT NULL,
`firstB` char(1) NOT NULL DEFAULT ''
) ENGINE=InnoDB DEFAULT CHARSET=utf8;
INSERT INTO `A` (`id`, `firstA`, `secondA`)
VALUES (1, 'a', 'b'), (2, 'c', 'd');
INSERT INTO `B` (`id`, `firstB`)
VALUES (1, 'x'), (1, 'y'), (2, 'z'), (2, 'v'), (4, 'w');
First create a view that joins the two tables:
create or replace view C_join as
select A.firstA, A.secondA, B.firstB
from A
join B on B.id=A.id;
Create the view that groups the rows in table B:
create or replace view d_group_concat as
select firstA, secondA, group_concat(firstB) groupconcat
from c_join
group by firstA, secondA
Create the view that does what you need:
create or replace view e_result as
select firstA, secondA, SUBSTRING_INDEX(groupconcat,',',1) firstB, SUBSTRING_INDEX(SUBSTRING_INDEX(groupconcat,',',2),',',-1) secondB
from d_group_concat
And that's all. Hope this helps you.
If you can't create views, this could be the query:
select firstA, secondA, SUBSTRING_INDEX(groupconcat,',',1) firstB, SUBSTRING_INDEX(SUBSTRING_INDEX(groupconcat,',',2),',',-1) secondB
from (
select firstA, secondA, group_concat(firstB) groupconcat
from (
select A.firstA, A.secondA, B.firstB
from A
join B on B.id=A.id
) c_join
group by firstA, secondA
) d_group_concat
Big thanks to everyone for the answers. James's answer was first, simplest and works perfectly in my case. The query runs several times faster than mine, with subqueries. Thanks, James!
Just a few words why I needed that:
It's a part of integration component for Prestashop and wholesale exchange platform. There are 4 product code systems that wholesalers use on the platform (ean13, upc and 2 other systems). Those 2 other product codes are added as product feature in Prestashop. There are thousands of products on the shop and hundreds of thousands of products on the platform. Which is why speed is crucial.
Here is the code for full version of my question. Maybe someone will find this helpful.
Query to get Prestashop product codes and certain features in one row:
SELECT
p.id_product, p.ean13, p.upc, fvl1.value as code1, fvl2.value as code2
FROM `ps_product` p
LEFT JOIN
`ps_feature_product` fp1 ON (p.id_product = fp1.id_product and fp1.id_feature = 24)
LEFT JOIN
`ps_feature_value_lang` fvl1 ON (fvl1.id_feature_value = fp1.id_feature_value)
LEFT JOIN
`ps_feature_product` fp2 ON (p.id_product = fp2.id_product and fp2.id_feature = 25)
LEFT JOIN
`ps_feature_value_lang` fvl2 ON (fvl2.id_feature_value = fp2.id_feature_value)
WHERE
ean13 != '' OR upc != '' OR fvl1.value IS NOT NULL OR fvl2.value IS NOT NULL;
Right now I'm creating an online game where I list the last transfers of players.
The table that handles the history of players, has the columns history_join_date and history_end_date.
When history_end_date is filled, it means that player left a club, and when it is like the default (0000-00-00 00:00:00) and history_join_date has some date it means player joined the club (in that date).
Right now, I've the following query:
SELECT
player_id,
player_nickname,
team_id,
team_name,
history_join_date,
history_end_date
FROM
players
INNER JOIN history
ON history.history_user_id = players.player_id
INNER JOIN teams
ON history.history_team_id = teams.team_id
ORDER BY
history_end_date DESC,
history_join_date DESC
LIMIT 7
However, this query returns something like (filtered with PHP above):
(22-Aug-2012 23:05): Folha has left Portuguese Haxball Team.
(22-Aug-2012 00:25): mancini has left United.
(21-Aug-2012 01:29): PatoDaOldSchool has left Reign In Power.
(22-Aug-2012 23:37): Master has joined Born To Win.
(22-Aug-2012 23:28): AceR has joined Born To Win.
(22-Aug-2012 23:08): Nasri has joined Porto Club of Haxball.
(22-Aug-2012 18:53): Lloyd Banks has joined ARRIBA.
PHP Filter:
foreach ($transfers as $transfer) {
//has joined
if($transfer['history_end_date']<$transfer['history_join_date']) {
$type = ' has joined ';
$date = date("d-M-Y H:i", strtotime($transfer['history_join_date']));
} else {
$type = ' has left ';
$date = date("d-M-Y H:i", strtotime($transfer['history_end_date']));
}
As you can see, in the transfers order, the date is not being followed strictly (22-Aug => 21-Aug => 22-Aug).
What am I missing in the SQL?
Regards!
The issue is you are ordering based upon two different values. So your results are ordered first by history_end_date, and when the end dates are equal (i.e. when it is the default value), they are then ordered by history_join_date
(Note that your first results are all ends, and then your subsequent results are all joins, and each subset is properly ordered).
How much control do you have over this data structure? You might be able to restructure the history table such that there is only a single date, and a history type of JOINED or END... You might be able to make a view of joined_date and end_date and sort across that...
From what you have in the question I made up the following DDL & Data:
create table players (
player_id INT NOT NULL AUTO_INCREMENT PRIMARY KEY,
player_nickname VARCHAR(255) NOT NULL UNIQUE
);
create table teams (
team_id INT NOT NULL AUTO_INCREMENT PRIMARY KEY,
team_name VARCHAR(255) NOT NULL UNIQUE
);
create table history (
history_id INT NOT NULL AUTO_INCREMENT PRIMARY KEY,
history_user_id INT NOT NULL, history_team_id INT NOT NULL,
history_join_date DATETIME NOT NULL,
history_end_date DATETIME NOT NULL DEFAULT "0000-00-00 00:00:00"
);
insert into players VALUES
(1,'Folha'),
(2,'mancini'),
(3,'PatoDaOldSchool'),
(4,'Master'),
(5,'AceR'),
(6,'Nasri'),
(7,'Lloyd Banks');
insert into teams VALUES
(1,'Portuguese Haxball Team'),
(2,'United'),
(3,'Reign In Power'),
(4,'Born To Win'),
(5,'Porto Club of Haxball'),
(6,'ARRIBA');
insert into history VALUES
(DEFAULT,1,1,'2012-08-01 00:04','2012-08-22 23:05'),
(DEFAULT,2,2,'2012-08-21 19:04','2012-08-22 00:25'),
(DEFAULT,3,3,'2012-08-19 01:29','2012-08-21 01:29'),
(DEFAULT,4,4,'2012-08-22 23:37',DEFAULT),
(DEFAULT,5,4,'2012-08-22 23:28',DEFAULT),
(DEFAULT,6,5,'2012-08-22 23:08',DEFAULT),
(DEFAULT,7,6,'2012-08-22 18:53',DEFAULT);
SOLUTION ONE - History Event View
This is obviously not the only solution (and you'd have to evaluate options as they suit your needs, but you could create a view in MySQL for your history events and join to it and use it for ordering similar to the following:
create view historyevent (
event_user_id,
event_team_id,
event_date,
event_type
) AS
SELECT
history_user_id,
history_team_id,
history_join_date,
'JOIN'
FROM history
UNION
SELECT
history_user_id,
history_team_id,
history_end_date,
'END'
FROM history
WHERE history_end_date <> "0000-00-00 00:00:00";
Your select then becomes:
SELECT
player_id,
player_nickname,
team_id,
team_name,
event_date,
event_type
FROM players
INNER JOIN historyevent
ON historyevent.event_user_id = players.player_id
INNER JOIN teams
ON historyevent.event_team_id = teams.team_id
ORDER BY
event_date DESC;
Benefit here is you can get both joins and leaves for the same player.
SOLUTION TWO - Pseudo column. use the IF construction to pick one or the other column.
SELECT
player_id,
player_nickname,
team_id,
team_name,
history_join_date,
history_end_date,
IF(history_end_date>history_join_date,history_end_date,history_join_date) as order_date
FROM
players
INNER JOIN history
ON history.history_user_id = players.player_id
INNER JOIN teams
ON history.history_team_id = teams.team_id
ORDER BY
order_date DESC;
Building from #Barmar's answer, you can also use GREATEST() to pick the greatest of the arguments. (MAX() is a grouping function... not actually what you're looking for)
I think what you want is:
ORDER BY MAX(history_join_date, history_end_date)
My current database looks like
CREATE TABLE sites(
siteId INT(11) AUTO_INCREMENT,
siteType VARCHAR(255),
siteName VARCHAR(255),
siteDomain VARCHAR(255),
PRIMARY KEY(siteId)
);
CREATE TABLE siteSites(
parentId INT(11),
childId INT(11)
)
I'm trying to join all the tables and fetch all data.
like:
<?php
$q=mysql_query("SELECT * FROM sites s1, siteSites, sites s2 WHERE s1.siteId=parentId AND s2.siteId=childId");
$row=mysql_fetch_array($q);
?>
and than i want to get both the info from 's1' and 's2' out of the $row variable.
is this possible and if it is than how do i do it?
thank you
SELECT s1.siteId as ParentSiteId, s1.siteType as ParentType, s1.siteName as ParentName, s1.siteDomain as ParentDomain,
s2.siteId as ChildSiteId, s2.siteType as ChildType, s2.siteName as ChildName, s2.siteDomain as ChildDomain
FROM sites s1
INNER JOIN siteSites ss
ON s1.siteId = ss.parentId
INNER JOIN sites s2
ON ss.childId = s2.siteId
Your question isn't very clear...
If I'm making any sense of it, you'd like to pull the entire graph in a single query. If so, no, this is not possible in MySQL. Doing so would require a recursive with statement.
If not and your current query is correct, you need to alias the column names rather than select *, i.e. something like:
select s1.siteid as parent_id,
s1.sitename as parent_name,
...,
s2.siteid as child_id,
s2.sitename as child_name,
...
I don't know if I understood your question.
Try this:
SELECT s1.*, s2.*
FROM sites s1 JOIN siteSites ss
ON s1.siteId = ss.parentId
JOIN sites s2
ON ss.childId = s2.siteId
You only missing the while loop:
while($row=mysql_fetch_array($q))
{
echo $row['siteName'];
echo $row['siteDomain'];
echo $row['parentId'];
// etc ..., access to values by field name
}
I have a mysql query:
$query = "SELECT * FROM movielist WHERE genre = 'comedy' ORDER BY dateadded DESC";
I need to change it so that it selects from movielist where genre contains 'comedy'.
(Note: that my genre field will often contain more than one genre example "comedy, action, drama".
You need to LIKE the genre:
$query = "SELECT * FROM movielist WHERE genre LIKE '%comedy%' ORDER BY dateadded DESC"
$query = "SELECT * FROM movielist WHERE genre LIKE '%comedy%' ORDER BY dateadded DESC";
OR
$query = "SELECT * FROM movielist WHERE FIND_IN_SET('comedy', genre) ORDER BY dateadded DESC";
Second one is better in most cases.
Even better, you should use a separate table for facilitating many-to-many relationships.
i.e. New table called 'movies_genres' with two fields - movie_id and genre_id (both indexed foreign keys). Every time you add a new genre to a movie or a new movie to a genre, add an entry to this table.
To find all movies belonging to a particular genre:
SELECT movies.*
FROM movies
JOIN movies_genres
ON movies_genres.movie_id = movies.id
JOIN genres
ON movies_genres.genre_id = genres.id
WHERE genres.name = 'comedy'
To find all genres belonging to a particular movie:
SELECT genres.*
FROM genres
JOIN movies_genres
ON movies_genres.genre_id = genres.id
JOIN topics
ON movies_genres.movie_id = movies.id
WHERE movies.name = 'Citizen Kane'
With your schema you might be interested in find_in_set()
SELECT
x,y,z
FROM
movielist
WHERE
find_in_list('comedy', genre)
Keep in mind that this is not index-friendly and potentially slow.
With normalized tables you wouldn't have genre='comedy, action, drama' (i.e. structured data within one field) but a table
genres (
id int auto_increment,
genre_name varchar(...)
...
)
a table
movielist (
id int auto_increment,
title varchar(...)
...
)
and a table
moviegenres (
movieid int,
genreid int,
...
)
And a query that "glues" the information stored in these three tables together using one or two JOINs.
For an immediate solution, do a Dexter suggested. But in the long run you will get a lot of benefit from normalizing your database