I'm running this SQL query
$sql = "select images.image, images.comment as feedDescription,
customers.fullName, CONCAT('[', GROUP_CONCAT(DISTINCT likes.uid),']') as likes,
CONCAT('[', GROUP_CONCAT(DISTINCT CONCAT('{\"userid\":\"', comments.fid, '\", \"comment\":\"', comments.comment, '\"}') separator ','),']') as comments
FROM images
LEFT JOIN customers on images.client_id = customers.client_id
LEFT JOIN likes on images.image = likes.image
LEFT JOIN comments on images.image = comments.image
WHERE images.fid=:userID
ORDER BY images.image LIMIT $offset,$limit";
the only problem is that I am getting only the first row ...
I have images table, customers table (taking the name of the customer by the id i got in the images), likes table (people who did "like" on the image) and comments (people who wrote "comments" on the table)
You are using an aggregation function on a query, so MySQL is automatically returning only one row -- the aggregation of all the data.
In other databases, this would produce an error, because you have a mixture of aggregated and non-aggregated columns. This is a (mis)feature of MySQL called "hidden columns".
Add a group by to your query to fix the problem:
group by images.image, images.comment, customers.fullName
Be sure to add this after the WHERE clause and before the ORDER BY.
Related
I've got 1 SQL command to select data from 2 different tables.
First table is "sections" (id, title, text) and second table is "sections_multimedia" (id, section_id, filename)
I use GROUP_CONCAT to get all the sections of the page and each one's multimedia (photos)
My command is the following:
SELECT s.*, GROUP_CONCAT(CONCAT_WS(':', sm.id, sm.filename) SEPARATOR ',') AS multimedia
FROM sections AS s, sections_multimedia AS sm
WHERE s.id = sm.section_id
GROUP BY sm.section_id
ORDER BY s.id ASC;
Table "sections" and table "sections_multimedia" are connected via "section_id" field of "sections_multimedia" table.
The above SQL command works perfectly, the only problem is:
When a row from "sections" table has nothing in table "sections_multimedia" it is not showed in the results.
What can i do to grab all data from table "sections" no matter if they have or not any data in "sections_multimedia" table?
Thank you!
Never use commas in the FROM clause. Always use proper, explicit JOIN syntax. In your case, you want a LEFT JOIN:
SELECT s.*,
GROUP_CONCAT(CONCAT_WS(':', sm.id, sm.filename) SEPARATOR ',') AS multimedia
FROM sections s LEFT JOIN
sections_multimedia sm
ON s.id = sm.section_id
GROUP BY s.id
ORDER BY s.id ASC;
have 3 following tables:
users (id, name)
projects (id, name)
user_to_project (user_id, project_id)
Every user can be assigned to more than one project and this is stored in the user_to_project table. I want to get a user name and all the projects he's assigned to in one field separated with commas. I tried something like this:
SELECT
users.id AS 'ID',
users.name AS 'Name',
(SELECT GROUP_CONCAT (projects.name SEPARATOR ', ')
FROM user_to_project
INNER JOIN projects ON (projects.id = user_to_project.project_id)
INNER JOIN users ON (users.id = user_to_project.user_id)) AS 'Projects'
FROM users
It gets me all assigned projects in every row which is not that I want. How to fix this?
You can do this with a subquery, but you want a correlation clause:
SELECT u.id, u.name,
(SELECT GROUP_CONCAT(p.name SEPARATOR ', ')
FROM user_to_project tup INNER JOIN
projects p
ON p.id = utp.project_id
WHERE u.id = utp.user_id
) as Projects
FROM users u;
Notes:
Use table aliases. They make a query easier to write and to read.
Don't use single quotes for column aliases. Only use single quotes for string and column names (and your column aliases don't require any escape character).
This is different from a version using INNER JOIN, because this will keep all users, even those with no projects.
I didn't see any reason for this correlated query, and you were missing a condition inside to relate it to the outer query. You also needed a group by clause.
This query should give you all the projects for each ID :
SELECT users.id, users.name ,
GROUP_CONCAT (projects.name SEPARATOR ', ')
FROM user_to_project
INNER JOIN projects ON (projects.id = user_to_project.project_id)
INNER JOIN users ON (users.id = user_to_project.user_id)
GROUP BY users.id,users.name
Note: To make your query work, all you need is to drop the users table from the inner query, and keep the condition.
I have three Tables:
Posts:
id, title, authorId, text
authors:
id, name, country
Comments:
id, authorId, text, postId
I want to run a mysql command which selects the first 5 posts which were written by authors, whose country is 'Ireland'. In the same call, I want to retrieve all the comments for those five posts, and also the author info.
I've tried the following:
SELECT posts.id as 'posts.id', posts.title as 'posts.title' (etc. etc. list all fields in three table)
FROM
(SELECT * FROM posts, authors WHERE authors.country = 'ireland' AND authors.id = posts.authorId LIMIT 0, 5 ) as posts
LEFT JOIN
comments ON comments.postId = posts.id,
authors
WHERE
authors.id = posts.authorId
I had to include every field with an alias ^ because there was a duplicate for id, and more fields in future may become duplicates as I'm looking for a generic solution.
My two questions are:
1) I am getting a duplicate field entry from within my subselect for id, so do I have to list out all my fields as aliases again within the subselect or is there only one field I need for a subselect
2) Is there a way to auto-alias my call? At the moment I've just aliased every field in the main select but can it do this for me so there are no duplicates?
Sorry if this isn't very clear it's a bit of a messy problem! Thanks.
You are doing an unnecessary join back to the author table in your query. You get all the fields you want in the posts subquery. I would rename this to something other than an existing table, perhaps pa to indicate posts and authors.
You say you want the first 5 posts, but have no order clause. A better form of the query is:
SELECT pa.id as 'posts.id', pa.title as 'posts.title' (etc. etc. list all fields in three table)
FROM (SELECT *
FROM posts join
authors
on authors.id = posts.authorId
WHERE authors.country = 'ireland'
order by post.date
LIMIT 0, 5
) pa LEFT JOIN
comments c
ON c.postId = pa.id
Note that this returns the first five posts and their authors (as specified in the question). But one author may be responsible for all five posts.
In MySQL, you can use * and it will get rid of duplicate aliases in the from clause. I think this is dangerous. It is better to list all the columns you want.
To answer your questions:
You can select as many (or as few) columns as you need from a sub-query
You do not need to join the authors table again since you already selected all fields in the sub-query (and so get rid of duplicate columns names).
A few additional remarks...
... about the JOIN syntax
Prefer the form
FROM t1 JOIN t2 ON (t1.fk = t2.pk)
to the obsolete, obscure
FROM t1, t2 WHERE t1.fk = t2.pk
... about the use of a LIMIT clause without an ORDER BY clause
The order in which rows are returned by a SELECT statement without an ORDER BY clause is undefined. Therefore, a LIMIT n clause without an ORDER BY clause could return any n rows in theory.
Your final query should look like this:
SELECT *
FROM (
SELECT *
FROM posts
JOIN authors ON (authors.id = posts.authorId )
WHERE authors.country = 'ireland'
ORDER BY posts.id DESC -- assuming this column is monotonically increasing
LIMIT 5
) AS last_posts
LEFT JOIN comments ON ( comments.postId = last_posts .id )
I have three tables that are joined. I almost have the solution but there seems to be one small problem going on here. Here is statement:
SELECT items.item,
COUNT(ratings.item_id) AS total,
COUNT(comments.item_id) AS comments,
AVG(ratings.rating) AS rate
FROM `items`
LEFT JOIN ratings ON (ratings.item_id = items.items_id)
LEFT JOIN comments ON (comments.item_id = items.items_id)
WHERE items.cat_id = '{$cat_id}' AND items.spam < 5
GROUP BY items_id ORDER BY TRIM(LEADING 'The ' FROM items.item) ASC;");
I have a table called items, each item has an id called items_id (notice it's plural). I have a table of individual user comments for each item, and one for ratings for each item. (The last two have a corresponding column called 'item_id').
I simply want to count comments and ratings total (per item) separately. With the way my SQL statement is above, they are a total.
note, total is the total of ratings. It's a bad naming scheme I need to fix!
UPDATE: 'total' seems to count ok, but when I add a comment to 'comments' table, the COUNT function affects both 'comments' and 'total' and seems to equal the combined output.
Problem is you're counting results of all 3 tables joined. Try:
SELECT i.item,
r.ratetotal AS total,
c.commtotal AS comments,
r.rateav AS rate
FROM items AS i
LEFT JOIN
(SELECT item_id,
COUNT(item_id) AS ratetotal,
AVG(rating) AS rateav
FROM ratings GROUP BY item_id) AS r
ON r.item_id = i.items_id
LEFT JOIN
(SELECT item_id,
COUNT(item_id) AS commtotal
FROM comments GROUP BY item_id) AS c
ON c.item_id = i.items_id
WHERE i.cat_id = '{$cat_id}' AND i.spam < 5
ORDER BY TRIM(LEADING 'The ' FROM i.item) ASC;");
In this query, we make the subqueries do the counting properly, then send that value to the main query and filter the results.
I'm guessing this is a cardinality issue. Try COUNT(distinct comments.item_id)
I have two tables, one for downloads and one for uploads. They are almost identical but with some other columns that differs them. I want to generate a list of stats for each date for each item in the table.
I use these two queries but have to merge the data in php after running them. I would like to instead run them in a single query, where it would return the columns from both queries in each row grouped by the date. Sometimes there isn't any download data, only upload data, and in all my previous tries it skipped the row if it couldn't find log data from both rows.
How do I merge these two queries into one, where it would display data even if it's just available in one of the tables?
SELECT DATE(upload_date_added) as upload_date, SUM(upload_size) as upload_traffic, SUM(upload_files) as upload_files
FROM packages_uploads
WHERE upload_date_added BETWEEN '2011-10-26' AND '2011-11-16'
GROUP BY upload_date
ORDER BY upload_date DESC
SELECT DATE(download_date_added) as download_date, SUM(download_size) as download_traffic, SUM(download_files) as download_files
FROM packages_downloads
WHERE download_date_added BETWEEN '2011-10-26' AND '2011-11-16'
GROUP BY download_date
ORDER BY download_date DESC
I want to get result rows like this:
date, upload_traffic, upload_files, download_traffic, download_files
All help appreciated!
Your two queries can be executed and then combined with the UNION cluase along with an extra field to identify Uploads and Downloads on separate lines:
SELECT
'Uploads' TransmissionType,
DATE(upload_date_added) as TransmissionDate,
SUM(upload_size) as TransmissionTraffic,
SUM(upload_files) as TransmittedFileCount
FROM
packages_uploads
WHERE upload_date_added BETWEEN '2011-10-26' AND '2011-11-16'
GROUP BY upload_date
ORDER BY upload_date DESC
UNION
SELECT
'Downloads',
DATE(download_date_added),
SUM(download_size),
SUM(download_files)
FROM packages_downloads
WHERE download_date_added BETWEEN '2011-10-26' AND '2011-11-16'
GROUP BY download_date
ORDER BY download_date DESC;
Give it a Try !!!
What you're asking can only work for rows that have the same add date for upload and download. In this case I think this SQL should work:
SELECT
DATE(u.upload_date_added) as date,
SUM(u.upload_size) as upload_traffic,
SUM(u.upload_files) as upload_files,
SUM(d.download_size) as download_traffic,
SUM(d.download_files) as download_files
FROM
packages_uploads u, packages_downloads d
WHERE u.upload_date_added = d.download_date_added
AND u.upload_date_added BETWEEN '2011-10-26' AND '2011-11-16'
GROUP BY date
ORDER BY date DESC
Without knowing the schema is hard to give the exact answer so please see the following as a concept not a direct answer.
You could try left join, im not sure if the table package exists but the following may be food for thought
SELECT
p.id,
up.date as upload_date
dwn.date as download_date
FROM
package p
LEFT JOIN package_uploads up ON
( up.package_id = p.id WHERE up.upload_date = 'etc' )
LEFT JOIN package_downloads dwn ON
( dwn.package_id = p.id WHERE up.upload_date = 'etc' )
The above will select all the packages and attempt to join and where the value does not join it will return null.
There is number of ways that you can do this. You can join using primary key and foreign key. In case if you do not have relationship between tables,
You can use,
LEFT JOIN / LEFT OUTER JOIN
Returns all records from the left table and the matched
records from the right table. The result is NULL from the
right side when there is no match.
RIGHT JOIN / RIGHT OUTER JOIN
Returns all records from the right table and the matched
records from the left table. The result is NULL from the left
side when there is no match.
FULL OUTER JOIN
Return all records when there is a match in either left or right table records.
UNION
Is used to combine the result-set of two or more SELECT statements.
Each SELECT statement within UNION must have the same number of,
columns The columns must also have similar data types The columns in,
each SELECT statement must also be in the same order.
INNER JOIN
Select records that have matching values in both tables. -this is good for your situation.
INTERSECT
Does not support MySQL.
NATURAL JOIN
All the column names should be matched.
Since you dont need to update these you can create a view from joining tables then you can use less query in your PHP. But views cannot update. And you did not mentioned about relationship between tables. Because of that I have to go with the UNION.
Like this,
CREATE VIEW checkStatus
AS
SELECT
DATE(upload_date_added) as upload_date,
SUM(upload_size) as upload_traffic,
SUM(upload_files) as upload_files
FROM packages_uploads
WHERE upload_date_added BETWEEN '2011-10-26' AND '2011-11-16'
GROUP BY upload_date
ORDER BY upload_date DESC
UNION
SELECT
DATE(download_date_added) as download_date,
SUM(download_size) as download_traffic,
SUM(download_files) as download_files
FROM packages_downloads
WHERE download_date_added BETWEEN '2011-10-26' AND '2011-11-16'
GROUP BY download_date
ORDER BY download_date DESC
Then anywhere you want to select you just need one line:
SELECT * FROM checkStatus
learn more.