I'm really unsure how best to go about writing this query. I have 3 tables and I need to run a query pulling data from one, based on conditions in the others.
Tables: surveys, survey_countries, survey_categories
surveys:
id | survey_id | network_id
survey_countries:
id | survey_id | network_id | country
survey_categories:
id | survey_id | network_id | category
(The survey_id in survey_countries and survey_categories relates to the survey_id column in the surveys table as opposed to the id column).
I need to retrieve data from surveys for a specific country and a specific category. Then I need to be able to UNION for other categories, but I guess I can do that later. My attempt:
SELECT surveys.*
FROM survey_countries
LEFT JOIN surveys ON survey_countries.survey_id = surveys.survey_id ANd survey_countries.network_id = surveys.network_id
LEFT JOIN survey_categories ON survey_countries.survey_id = surveys.survey_id AND survey_categories.network_id = surveys.network_id
WHERE survey_countries.country = 'GB'
AND survey_categories.category = 'my_category'
GROUP BY surveys.id
Thanks!
EDIT: the following seems to work:
SELECT s.*, ca.category, co.country
FROM surveys s
LEFT JOIN survey_countries co ON s.survey_id = co.survey_id AND s.network_id = co.network_id
LEFT JOIN survey_categories ca ON s.survey_id = ca.survey_id AND s.network_id = ca.network_id
WHERE ca.category = 'uncategorised'
AND co.country = 'GB';
I'm just not sure it's the best way to do it since I need to grab surveys with multiple categories later on?
Without example data and an example output, helping you on this query is very difficult. However..... your 2nd join relates survey_countries with surveys. I think you mean to join it to the survey_categories. Also, you have a Group By, with no aggregate functions. Get rid of it until you have too much information an need to summarize columns
I am not saying this is correct, but it is slightly more 'correct' than yours
SELECT surveys.*
FROM survey_countries
LEFT JOIN surveys
ON survey_countries.survey_id = surveys.survey_id
AND survey_countries.network_id = surveys.network_id
LEFT JOIN survey_categories
ON survey_categories.survey_id = surveys.survey_id
AND survey_categories.network_id = surveys.network_id
WHERE survey_countries.country = 'GB'
AND survey_categories.category = 'my_category'
(If you can, load up a schema and sample data in sqlfiddle. It will make this problem easier to solve.)
Related
I want to display a set of data in a single row, but I don't seem to implement it, I tried several ways, it still doesn't work. I want to display all permission names assigned for a role name in a single row.
for example :
| editor | edit-user, delete-user, delete-role |
| deleter | delete-user |
here's my sql
$datas = DB::SELECT(' SELECT roles.id, roles.name as roleName, permissions.name as PermName
FROM roles
LEFT JOIN role_has_permissions
ON (roles.id = role_has_permissions.role_id)
LEFT JOIN permissions
ON (role_has_permissions.permission_id = permissions.id)
ORDER BY roles.id');
thank you in advance :)
Can you join the two middle joins in a subquery:
LEFT JOIN (
SELECT
permissions.name as PermName
,role_has_permissions.role_id
FROM role_has_permissions
LEFT JOIN permissions ON role_has_permissions.permission_id = permissions.id)
ON roles.id = role_has_permissions.role_id
I have an instrument list and teachers instrument list.
I would like to get a full instrument list with id and name.
Then check the teachers_instrument table for their instruments and if a specific teacher has the instrument add NULL or 1 value in a new column.
I can then take this to loop over some instrument checkboxes in Codeigniter, it just seems to make more sense to pull the data as I need it from the DB but am struggling to write the query.
teaching_instrument_list
- id
- instrument_name
teachers_instruments
- id
- teacher_id
- teacher_instrument_id
SELECT
a.instrument,
a.id
FROM
teaching_instrument_list a
LEFT JOIN
(
SELECT teachers_instruments.teacher_instrument_id
FROM teachers_instruments
WHERE teacher_id = 170
) b ON a.id = b.teacher_instrument_id
my query would look like this:
instrument name id value
--------------- -- -----
woodwinds 1 if the teacher has this instrument, set 1
brass 2 0
strings 3 1
One possible approach:
SELECT i.instrument_name, COUNT(ti.teacher_id) AS used_by
FROM teaching_instrument_list AS i
LEFT JOIN teachers_instruments AS ti
ON ti.teacher_instrument_id = i.id
GROUP BY ti.teacher_instrument_id
ORDER BY i.id;
Here's SQL Fiddle (tables' naming is a bit different).
Explanation: with LEFT JOIN on instrument_id we'll get as many teacher_id values for each instrument as teachers using it are - or just a single NULL value, if none uses it. The next step is to use GROUP BY and COUNT() to, well, group the result set by instruments and count their users (excluding NULL-valued rows).
If what you want is to show all the instruments and some flag showing whether or now a teacher uses it, you need another LEFT JOIN:
SELECT i.instrument_name, NOT ISNULL(teacher_id) AS in_use
FROM teaching_instrument_list AS i
LEFT JOIN teachers_instruments AS ti
ON ti.teacher_instrument_id = i.id
AND ti.teacher_id = :teacher_id;
Demo.
Well this can be achieved like this
SELECT
id,
instrument_name,
if(ti.teacher_instrument_id IS NULL,0,1) as `Value`
from teaching_instrument_list as til
LEFT JOIN teachers_instruments as ti
on ti.teacher_instrument_id = til.id
Add a column and check for teacher_instrument_id. If found set Value to 1 else 0.
I've been working on a project that until now has only needed to find 1 row from the joined table. But now I need to grab multiple rows..
So as it stand my sql works something like:
Select rows for each company for this particular project which alone would find company details (name, id, telephone.. blah).
Then I join a table that contains form data submitted for each company (multiple forms - so multiple records)
Until now i have been specifying one formid to look for in the join, but now i need to specify multiple ones.
If I use WHERE form_id = 1 OR form_id = 2 OR form_id = 3 ... I get a result of only the first form match that is found per company..
If I mix up the query so it looks for the forms 1st and returns multiple records for each company with different form data - that works in this sense..
But I am then looping through this array in a view and creating a table row per record (previously each row was a new company) but using the latter would cause multiple records to show for the same company.
Any way I can do this? I tried group by with the latter method but this results in only 1 record again.
SELECT DISTINCT p.project_company_has_user_id, p.project_company_has_user_project_id, p.project_company_has_user_user_id, c.company_id, c.company_hall_no, c.company_company_name, c.company_type, c.company_country, c.company_stand_number, c.company_image_file_1, p2.project_id, p2.project_name, u.user_id, u.user_username, o.orders_id, o2.order_detail_id, o2.order_detail_product_id, f2.form_question_has_answer_id, f2.form_question_has_answer_request, f2.form_question_has_answer_form_id, f2.form_question_has_answer_user_id
FROM project_company_has_user p
INNER JOIN company c ON p.project_company_has_user_company_id = c.company_id
INNER JOIN project p2 ON p.project_company_has_user_project_id = p2.project_id
INNER JOIN user u ON p.project_company_has_user_user_id = u.user_id
INNER JOIN form f ON p.project_company_has_user_project_id = f.form_project_id
LEFT JOIN orders o ON p.project_company_has_user_user_id = o.orders_user_id
LEFT JOIN order_detail o2 ON ((o2.order_detail_orders_id = o.orders_id AND (o2.order_detail_product_id = 65 OR o2.order_detail_product_id = 68 OR o2.order_detail_product_id = 64)))
LEFT JOIN form_question_has_answer f2 ON ((f2.form_question_has_answer_form_id = 297 AND f2.form_question_has_answer_user_id = p.project_company_has_user_user_id))
WHERE (f.form_template_name = "custom" AND p.project_company_has_user_garbage_collection = 0 AND p.project_company_has_user_project_id = 48) AND (LCASE(c.company_country) LIKE "%uk%" OR LCASE(c.company_country) LIKE "%uk%") ORDER BY company_company_name asc
you need another field in order_detail as o2 . this field is row_index(position),etc for positioning record
LEFT JOIN order_detail o2 ON (o2.row_index=1 AND (o2.order_detail_orders_id = o.orders_id AND (o2.order_detail_product_id = 65 OR o2.order_detail_product_id = 68 OR o2.order_detail_product_id = 64)))
Personally I would use an Outer Join for the table of which elements you need to list all matches. Should you them need to clean up that data you can build the logic into the Join Condition (as step 2). Depending on the volume of data you are handling and whether or not you need to reuse it later in the same proc, you may want to post that primary dataset into a temp table and use that as source (primary) for your later logic.
Hope that helps. If you need the code, let me know, but it is pretty straight forward.
Regards
Mac
I have a hard nut to crack with joing 3 tables.
I have a newsletter_items, newsletter_fields and newsletter_mailgroups which I want to be joined to get a list of newsletters.
The newsletter_items contains the fields:
letter_id, letter_date, receivers, template, status
That can look like
1, 1234567899, 1,2 (comma separated), standard.html, 1
newsletter_fields contains the fields:
field_uid, field_name, field_content, field_letter_uid
That can look like
1, letter_headline, A great headline, 1
where field_letter_uid is the newsletter for which the field belongs to.
and newsletter_mailgroups contains the fields:
mailgroup_id, mailgroup_name, number_of_members
That can look like
1, Group1, 233
2, Group2, 124
3, Group3, 54
What I want is to combine these 3 tables to that I can get a list of all the newsletter like this:
Letter date | Letter headline | Receivers | Status
2008-01-01 12:00:00 | A great headline | Group1, Group 2 | 1
So in short I want my SQL query to join the 3 tables and in that process select the receivers from the mailgroup table and display them comma separated like Group1, Group 2
This what I got now
SELECT A.*, B.* FROM newsletter_items A, newsletter_fields B, WHERE B.field_letter_uid = A.letter_id AND field_name = 'letter_headline' AND A.template = '". $template ."';
But I can't seem to figure out how to get the mailgroups into that.
I recommend that you make your joins explicit.
It makes it easier to debug your query and to change inner with left joins.
There is absolutely never a good reason to use SQL '89 implicit join syntax.
SELECT ni.*
, nf.*
, group_concat(nm.mailgroup_name) as mailgroups
FROM newsletter_items ni
INNER JOIN newsletter_fields nf
ON (nf.field_letter_uid = ni.letter_id)
INNER JOIN newsletter_mailgroups nm
ON (find_in_set(nm.mailgroup_id, ni.receivers))
WHERE
nf.field_name = 'letter_headline'
ni.template = '". $template ."'
GROUP BY ni.letter_id;
Regarding your database design.
I recommend you normalize your database, that means that you move the comma separated fields into a different table.
So you make a table receivers
Receivers
----------
id integer auto_increment primary key
letter_id integer not null foreign key references newsletter_items(letter_id)
value integer not null
You then remove the field receiver from the table newsletter_items
Your query then changes into:
SELECT ni.*
, group_concat(r.value) as receivers
, nf.*
, group_concat(nm.mailgroup_name) as mailgroups
FROM newsletter_items ni
INNER JOIN newsletter_fields nf
ON (nf.field_letter_uid = ni.letter_id)
INNER JOIN newsletter_mailgroups nm
ON (find_in_set(nm.mailgroup_id, ni.receivers))
LEFT JOIN receiver r ON (r.letter_id = ni.letter_id)
WHERE
nf.field_name = 'letter_headline'
ni.template = '". $template ."'
GROUP BY ni.letter_id;
This change should also speed up your query significantly.
If it's allowed, why don't you create a new table called newsletter_item_receivers where you could store letter_id, receiver_id fields?
Having comma separated values in a field like this usually means you're missing a table :)
Edit:
By using CSV, you are making your life miserable when you want to retrieve an answer to "give me all newsletters that receiver_id=5 receives" :)
Here's a good answer to a similar question on SO: Comma separated values in a database field
Edit2:
If I understand your table relationships correctly then it would be something like this:
SELECT
a.letter_date,
b.receiver_id,
a.status
FROM newsletter_items_receivers b
LEFT OUTER JOIN newsletter_items a ON (a.letter_id = b.letter_id)
LEFT OUTER JOIN newsletter_mailgroups m ON (m.mailgroup_id = b.receiver_id)
NOTE! This query WILL NOT return a newsletter when there are no receivers of that newsletter.
If you need that functionality you can try something like this:
SELECT
x.letter_date,
y.mailgroup_name,
x.status
FROM (
SELECT
a.letter_date,
b.receiver_id,
a.status
FROM newsletter_items a
LEFT OUTER JOIN newsletter_items_rec b ON (b.letter_id = a.letter_id)) x
LEFT OUTER JOIN newsletter_mailgroups y ON (y.mailgroup_id = x.receiver_id)
I don't have access to SQL right now so I might have made some syntax errors (hopefully not logical ones :)).
As for why we are doing it like this, as #Konerak pointed out, you'd be well advised to read up on database normalization and why it's important.
You can start with this article from about.com, just glanced over it seems an OK read
http://databases.about.com/od/specificproducts/a/normalization.htm
Also, it would be good if you'd keep fields names the same across multiple tables.
For example you have letter_id in newsletter_items, but you have field_letter_uid in newsletter_fields. Just a thought :)
Try to use
SELECT A.*, B.*, group_concat(C.mailgroup_name SEPARATOR ',')
FROM newsletter_items A, newsletter_fields B, newsletter_mailgroups C
WHERE B.field_letter_uid = A.letter_id
AND field_name = 'letter_headline'
AND A.template = '". $template ."'
and find_in_set(c.mailgroup_id, A.receivers)
group by A.letter_id;
I'm trying to join two tables. The first table has a list of 11 items which are 'site_names' with an auto id field of 'id'. The second table that I want to connect has an auto id field of 'desc_id' and another field of 'descriptions'. This second table currently has 3 rows of data that I want displayed only for id 1 in table 1.
So, I want to accomplish is to connect the first site in table one with an id of '1' to the entire second table.
I can't seem to figure out how connect only the first entry(id=1) in table 1 to all the rows in table 2 (tb.1->id->1 to tbl.2->desc_id->1,2,3).
I hope that made sense. Any help would be great. Thanks
Try:
select site_name, descriptions
from table_1
inner join table_2
on 1 = 1
where table_1.site_id = 1
This should join give you what you want.
OK - based on the comment, I'm guessing what you want is:
site1 | desc1 | desc2 | desc3
all on one row. This is a bit trickier - particularly if you want it to remain open to an arbitrary number of descriptions. For just 3 (or, really, any limited subset, but as the number goes up, it gets ugly), you could do:
select site_name, t2.desc, t3.desc, t4.desc
from table_1
inner join table_2 t2
on t2.desc_id = 1
inner join table_2 t3
on t3.desc_id = 2
inner join table_2 t4
on t4.desc_id = 3
where site_id = 1
This kind of stuff is highly irregular though. It seems to me like something about your schema is probably not quite right to generate this sort of requirement.
Here is the query:
<?php
$mysql = new mysqli('localhost', 'root', 'root') or die('counld not connect');
$result = $mysql->query("SELECT ajax_demo.explore.site_name, anthony1.property.descriptions FROM ajax_demo.explore INNER JOIN anthony1.property ON ajax_demo.explore.id = anthony1.property.desc_id") or die($mysql->error);
if($result)
{
while($row = $result->fetch_object())
{
$id = $row->id;
$siteName = $row->site_name;
$siteDescription = $row->site_description;
echo "$siteName";
echo "$siteDescription";
}
}
?>
I may be missing something here, but it sounds to me like you need to add a foreign key to the Site table. If I understand your question correctly, your tables should look something like this:
Site
- SiteID
- DescriptionID
- SiteName
Description
- DescriptionID
- Description
Then your query to get Sites and their associated Descriptions would look like this:
SELECT
s.SiteName,
d.Description
FROM
Site s INNER JOIN Description d
ON s.DescriptionID = d.DescriptionID
This table structure assumes that multiple Sites share single Descriptions (as per your posted question).