I have written a query which returns all records with some many-to-many joins correctly for the entire set or an individual article using WHERE a.id = ?
SELECT a.id, date_added, title, content, category_id, person_id, organization_id, c.name AS category_name, firstname, lastname, o.name AS organization_name
FROM articles AS a
LEFT OUTER JOIN articles_categories AS ac ON a.id=ac.article_id
LEFT OUTER JOIN categories AS c ON c.id=ac.category_id
LEFT OUTER JOIN articles_people AS ap ON a.id=ap.article_id
LEFT OUTER JOIN people AS p ON p.id=ap.person_id
LEFT OUTER JOIN articles_organizations AS ao ON a.id=ao.article_id
LEFT OUTER JOIN organizations AS o ON o.id=ao.organization_id
ORDER BY date_added
BUT!
I've hit a brick wall trying to work out how to limit the articles to a specific number of IDs, for working with pagination.
I'm ideally trying to use as simple and clear SQL statements as possible because I'm using the codeigniter framework with their active record class.
http://codeigniter.com/user_guide/database/active_record.html
Would really appreciate some help as I don't want to revert to using multiple queries for this as I've tried to reduce it down to a single query for database efficiency.
Have search around and tried some alternatives but nothing seems to work. Many thanks!
For example the results I return are like this
---------------------------------------------------------------------
id title category_id person_id organization_id
---------------------------------------------------------------------
1 test 1 1 1
1 test 2 1 1
1 test 1 2 1
1 test 1 1 2
1 test 5 1 1
1 test 8 1 1
1 test 1 4 1
1 test 1 4 2
1 test 1 1 1
2 test 2 2 1 1
2 test 2 1 2 1
2 test 2 1 1 2
2 test 2 5 1 1
2 test 2 8 1 1
2 test 2 1 4 1
2 test 2 1 4 2
I need the results like this so that I can create sub-arrays in the php like this:
$articles = $query->result_array();
$output = array();
foreach ($articles as $article) {
// set up article details
$article_id = $article['id'];
// add article details
$output[$article_id]['article_id'] = $article_id;
$output[$article_id]['date_added'] = $article['date_added'];
$output[$article_id]['title'] = $article['title'];
$output[$article_id]['content'] = $article['content'];
// set up people details and add people array with details if exists
if (isset($article['person_id'])) {
$person_id = $article['person_id'];
$output[$article_id]['people'][$person_id]['person_id'] = $person_id;
$output[$article_id]['people'][$person_id]['lastname'] = $article['lastname'];
$output[$article_id]['people'][$person_id]['firstname'] = $article['firstname'];
}
// set up organizations details and add organizations array with details if exists
if (isset($article['organization_id'])) {
$organization_id = $article['organization_id'];
$output[$article_id]['organizations'][$organization_id]['organization_id'] = $organization_id;
$output[$article_id]['organizations'][$organization_id]['organization_name'] = $article['organization_name'];
}
// set up categories details and add categories array with details if exists
if (isset($article['category_id'])) {
$category_id = $article['category_id'];
$output[$article_id]['categories'][$category_id]['category_id'] = $category_id;
$output[$article_id]['categories'][$category_id]['category_name'] = $article['category_name'];
}
}
But if I just use LIMIT (with offset etc) 1
the results I get are
---------------------------------------------------------------------
id title category_id person_id organization_id
---------------------------------------------------------------------
1 test 1 1 1
instead of
---------------------------------------------------------------------
id title category_id person_id organization_id
---------------------------------------------------------------------
1 test 1 1 1
1 test 2 1 1
1 test 1 2 1
1 test 1 1 2
1 test 5 1 1
1 test 8 1 1
1 test 1 4 1
1 test 1 4 2
1 test 1 1 1
which is my desired result.
OK, so finally I worked out how it is possible.
Thought i'd include it here in case anyone else has the same problem.
Changing this line
FROM articles AS a
to this
FROM (SELECT * FROM articles LIMIT 5,3) AS a
does what I wanted.
So, why don't you use OFFSET 0,10 and LIMIT *number_of_results* in the SQL Query? (if I understood the question)
Specific number of IDs... WHERE ID IN (2,4,6,8)... ?
Are you using codeigniter's pagination?
http://codeigniter.com/user_guide/libraries/pagination.html
You can easily limit the number of records that are being returned using the MySQL LIMIT clause. This can be achieved like the following with your sample query.
SELECT a.id, date_added, title, content, category_id, person_id, organization_id, c.name AS category_name, firstname, lastname, o.name AS organization_name
FROM articles AS a
LEFT OUTER JOIN articles_categories AS ac ON a.id=ac.article_id LEFT OUTER JOIN categories AS c ON c.id=ac.category_id
LEFT OUTER JOIN articles_people AS ap ON a.id=ap.article_id LEFT OUTER JOIN people AS p ON p.id=ap.person_id
LEFT OUTER JOIN articles_organizations AS ao ON a.id=ao.article_id LEFT OUTER JOIN organizations AS o ON o.id=ao.organization_id
ORDER BY date_added
LIMIT 10
Where 10 is the number of records you wish to display. The MySQL LIMIT clause allows you to specify a limit of the number of records and an initial offset. Like so:
LIMIT <offset>,<limit>
In your case <offset> would be the current page * the number of records on a page. <limit> would be the number of records you would like to display per page.
Related
Is it possible to limit number of records based on parent/child relationship;
I have a simple comments table:
id parent_id
==============
1 0
2 1
3 1
4 0
5 4
6 4
and my query:
SELECT
id,
parent_id
FROM
comments
ORDER BY parent_id LIMIT 0,5;
The problem is, since comments are nested, it will cut of in a middle of child comment. What I would like is, to select x number of items, but to include children as well.
SELECT kid.*
FROM 0_a AS kid
JOIN (
SELECT id FROM 0_a WHERE root_id = 0 LIMIT 5
) AS p ON kid.id = p.id OR kid.root_id = p.id
ORDER BY kid.id
I currently have 2 tables in a database I need to get information from, "content" and "type". These two tables are linked by a 3rd table name "typeMembers." This is the structure:
Table Content:
id content link date isPublished
1 content 1 link 1 3/13/91 1
2 content 2 link 2 3/18/91 1
3 content 3 link 3 3/22/91 1
Table type:
id name
1 Event
2 Page
3 Test
Table typeMember
id type_id content_id
1 1 1
2 2 1
3 3 1
4 1 2
5 1 3
Currently I have my query set up as:
//using PDO in PHP
q = $dbc->prepare(
"SELECT a.id, a.content,a.date,a.link, c.name
FROM content a
LEFT OUTER JOIN typeMember b
ON b.content_id = a.id
LEFT OUTER JOIN types c
ON b.type_id = c.id
WHERE a.isPublished = 1
ORDER BY a.date DESC"
);
$r = $q->execute();
When this is returned I am getting 1 row for each typeMember in the database instead of content. What am I structuring wrong?
Data I would like to be returned:
id content link date name
1 content 1 link 1 3/13/91 Event, Page, Test
2 content 2 link 2 3/18/91 Event
3 content 3 link 3 3/22/91 Event
How it is being returned
id content link date name
1 content 1 link 1 3/13/91 Event
1 content 1 link 1 3/13/91 Page
1 content 1 link 1 3/13/91 Test
2 content 2 link 2 3/18/91 Event
3 content 3 link 3 3/22/91 Event
Edit: filing out the data actually made me realize what is going on. There is a 1 to many relationship with content to type. Is there a way to get all the types in one query?
for get the name in the same row you can use group_Concat
SELECT a.id, a.content, a.date, a.link, group_concat(c.name )
FROM content a
LEFT JOIN typeMember b ON b.content_id = a.id
LEFT JOIN types c ON b.type_id = c.id
WHERE a.isPublished = 1
Group by a.id, a.content, a.date, a.link
ORDER BY a.date DESC
Music table
id | title
1 Rap God
2 Blank Space
3 Bad Blood
4 Speedom
5 Hit 'em up
Like table
u_id | m_id
1 1
1 2
1 4
1 5
2 3
2 4
2 5
3 1
3 5
4 1
4 2
4 5
Now if someone visits music with m_id = 1
Then the output might be like
m_id
5
2
4
To explain this a bit...
As m_id = 1 is liked by users -> {1,3,4} which in turn likes ->{2,4,5} musics. Since m_id=5 is liked by max number of users its first followed by m_id = 2 and m_id = 4.
My Try
I queried the users who liked m_id = 1
SELECT u_id FROM likes WHERE m_id =1
Then i stored in in an array and selected each of their likes and
arranged them in desc order of count.
But it is a very slow and long process is there any way i can do this ?
p.s I have heard of Association Rules and Bayesian theorem can be user to achieve this. But can anyone help me out with an example ?
You can JOIN back on the Like table and do something like this.
SELECT also_like.m_id, COUNT(also_like.m_id)
FROM [like] AS did_like
JOIN [like] AS also_like ON
also_like.u_id = did_like.u_id
AND also_like.m_id != did_like.m_id
WHERE did_like.m_id = 1
GROUP BY also_like.m_id
ORDER BY COUNT(also_like.m_id)
Essentially you are getting a list of users who liked an item then getting a complete list of those user's likes excluding the item they just liked.
You can then add a HAVING clause or LIMIT to filter things down a bit more.
using a subquery ...
SELECT m_id, count(u_id) as Rank FROM `like`
WHERE u_id in
(
SELECT u_id
FROM `like`
WHERE m_id = 1
)
AND m_id <> 1
GROUP BY m_id
ORDER BY Rank DESC
and optionally
LIMIT 0, 10
or how many "alsolikes" you want to display
I have multiple tables with orders and deliveries and I want to get only open orders (only those orders that do not have records in delivery table).
So, my tables look like:
Orders table (sh_comenzi):
id partner
1 Partner X
2 Partner Y
3 Partner Z
4 Partner Q
Order lines table (sh_comenzi_pos) where idc is the id of sh_comenzi table
id idc cPos quantity
1 1 1 5
2 1 2 10
3 1 3 20
4 2 1 10
5 2 2 15
6 3 1 10
7 3 2 5
8 3 3 8
9 4 1 15
The deliveries items table is (sh_delivery_items)
id idc cPos
1 1 1
2 1 3
3 2 2
4 3 1
5 3 2
6 3 3
The desired result should give me an output of open orders just like this:
id partner
1 Partner X
2 Partner Y
4 Partner Q
The result doesn't have to keep track o quantities, just on lines level. If one line from orders exists in sh_delivery_items then that line is closed.
I tried something like this:
SELECT DISTINCT sh_comenzi.id, partner FROM sh_comenzi
LEFT JOIN sh_comenzi_pos ON sh_comenzi.id = sh_comenzi_pos.idc
LEFT JOIN sh_delivery_items ON (sh_comenzi_pos.idc = sh_delivery_items.idc AND sh_comenzi_pos.cPos = sh_delivery_items.cPos)
WHERE sh_comenzi.id IS NOT NULL
ORDER BY sh_comenzi.id DESC
Could someone help me?
This is the query you need:
SELECT DISTINCT c.*
FROM sh_comenzi c
INNER JOIN sh_comenzi_pos p
ON c.id = p.idc
LEFT JOIN sh_delivery_items di # 'di' from 'delivery items'
ON p.idc = di.idc AND p.cPos = di.cPos
WHERE di.id IS NULL # keep only not-delivered items
How it works
It combines all the orders (table sh_comenzi) with their line items (table sh_comenzi_pos). The INNER JOIN will leave out the empty orders (if any); if you need them then use LEFT JOIN instead.
Next, each row (order, line item) is combined with the delivery information (table sh_delivery_items) using the pair of columns (idc, cPos). The LEFT JOIN ensures all the rows from the left side table (or result set) appear in the final result set; if a row from the right side table cannot be found to match the row from the left, a row full of NULLs is used instead. This happens for the line items that were not delivered yet (there is no record for them in sh_delivery_items).
Then, the WHERE clause keeps only the rows having NULLs in the di table (sh_delivery_items), i.e. the line items that were not delivered, together with the orders that own them.
Finally, SELECT DISTINCT c.* selects only the columns from the orders table (sh_comenzi) and DISTINCT ensures each order appear only once. Otherwise, each order appears once for each of its line items that was not delivered.
Complete the query yourself with the desired ORDER BY clause.
I have this table:
This selection is is duplicated many times for different var_lines (which pretty much work as one row of data, or respondent for a survey) and set_codes (different survey codes).
With this query:
SELECT
*, COUNT(*) AS total
FROM
`data`
WHERE
`var_name` = 'GND.NEWS.INT'
AND(
`set_code` = 'BAN11A-GND'
OR `set_code` = 'BAN09A-GND'
OR `set_code` = 'ALG11A-GND'
)
AND `country_id` = '5'
GROUP BY
`data_content`,
`set_code`
ORDER BY
`set_code`,
`data_content`
The query basically counts the number of answers for a specific question. Then groups them survey (set_code).
What I need is for each of the grouped data_content answers for GND.NEWS.INT to also show the SUM of all the corresponding GND_WT with the same var_line.
For example if I had this:
data_id data_content var_name var_line
1 2 GND.NEW.INT 1
2 1.4 GND_WT 1
3 2 GND.NEW.INT 2
4 1.6 GND_WT 2
5 3 GND.NEW.INT 3
6 0.6 GND_WT 3
I would get something like this:
data_id data_content var_name var_line total weight
1 2 GND.NEW.INT 1 2 3
5 3 GND.NEW.INT 3 1 0.6
Thanks for any help.
Your requirements are not exactly clear, but I think the following gives you what you want:
select d1.data_id,
d1.data_content,
d1.var_name,
d1.var_line,
t.total,
w.weight
from data d1
inner join
(
select data_content,
count(data_content) Total
from data
group by data_content
) t
on d1.data_content = t.data_content
inner join
(
select var_line,
sum(case when var_name = 'GND_WT' then data_content end) weight
from data
group by var_line
) w
on d1.var_line = w.var_line
where d1.var_name = 'GND.NEW.INT'
See SQL Fiddle with Demo
This Query can be suitable for your specific example:
select st.data_id,
st.data_content,
st.var_name,
st.var_line,
count(st.data_id) as total,
sum(st1.data_content) as weight
from data st
left join data st1 on st1.var_name = 'GND_WT' AND st1.var_line=st.var_line
where st.var_name='GND.NEW.INT'
group by st.data_content
Regards,
Luis.