I have total 6 tables in which different info has been saved
Now i need a result in which get count from 5 tables and select all info from main table but if record does not exist than it must be need to return 0 instead of no row found that's the problem here
I have tried below query but didn't get success
SELECT
u.*,
COUNT(DISTINCT c.id) as comments,
COUNT(DISTINCT d.id) as dislikes,
COUNT(DISTINCT l.id) as likes,
COUNT(DISTINCT s.id) as shares,
COUNT(DISTINCT t.id) as tags
FROM
job_details as u
JOIN job_comments as c ON u.id = c.job_id
JOIN job_dislike as d ON u.id = d.job_id
JOIN job_like as l ON u.id = l.job_id
JOIN job_share as s ON u.id = s.job_id
JOIN job_tags as t ON u.id = t.job_id
WHERE
u.id = c.job_id AND
u.id = d.job_id AND
u.id = l.job_id AND
u.id = s.job_id AND
u.id = t.job_id
GROUP BY
u.id
This query is executed, but didn't get exact result.
I don't quite understand why.
I was hoping somebody here could help me out?
Thanks!
You probably didn't get the exact result because some tables may be missing values.
Although you can solve this problem with a LEFT JOIN, the safer solution is to pre-aggregate the data:
SELECT u.*, c.comments, d.dislikes, l.likes, s.shares, t.tags
FROM job_details as u LEFT JOIN
(select c.job_id, count(*) as comments from job_comments group by c.job_id
) c
ON u.id = c.job_id LEFT JOIN
(select d.job_id, count(*) as dislikes from job_dislike d group by d.job_id
) d
ON u.id = d.job_id LEFT JOIN
(select l.job_id, count(*) as likes from job_like l group by l.job_id
) l
ON u.id = l.job_id LEFT JOIN
(select s.job_id, count(*) as shares from job_share s group by s.job_id
) s
ON u.id = s.job_id LEFT JOIN
(select t.job_id, count(*) as tags from job_tags t group by t.job_id
) t
ON u.id = t.job_id;
Why is this better? Consider an id that has 5 comments, likes, dislikes, shares and tags. The JOIN approach produces an intermediate result with 5*5*5*5*5 = 3,125 intermediate rows. Things can really get out of hand for popular ids.
Use LEFT JOIN instead of JOIN. and you don't need WHERE clause since you have joined those tables. And, use IFNULL function to return 0 for null values. You need to modify you query like this :
SELECT u.id,
IFNULL(COUNT(DISTINCT c.id),0) as comments,
IFNULL(COUNT(DISTINCT d.id),0) as dislikes,
IFNULL(COUNT(DISTINCT l.id),0) as likes,
IFNULL(COUNT(DISTINCT s.id),0) as shares,
IFNULL(COUNT(DISTINCT t.id),0) as tags
FROM job_details as u
LEFT JOIN job_comments as c ON u.id = c.job_id
LEFT JOIN job_dislike as d ON u.id = d.job_id
LEFT JOIN job_like as l ON u.id = l.job_id
LEFT JOIN job_share as s ON u.id = s.job_id
LEFT JOIN job_tags as t ON u.id = t.job_id
GROUP BY u.id
Related
I am trying to get a count of the number of logins during a given timeframe, currently my SQL query displays only results that had at least one login, I'd like it to display even those which have zero logins.
Query i'm using:
SELECT c.FullName, COUNT(l.Id)
FROM LoginsTable l JOIN UsersTable u ON u.Email = l.Email JOIN Organisations c ON c.Id = u.OrganisationId
WHERE l.AttemptTime > "2019-10-01" AND l.AttemptTime < "2019-11-01" AND l.Success = 1
GROUP BY c.Name
ORDER BY c.Name ASC;
You have a few issues. Firstly, you either need to use a RIGHT JOIN from LoginsTable or reorder the JOINs to put the JOIN to LoginsTable last and use a LEFT JOIN. Given the nature of your query the latter probably makes more sense.
Secondly, you need to put any conditions on fields from a table which has been LEFT JOINed into the join condition, otherwise MySQL converts the LEFT JOIN into an INNER JOIN (see the manual). Finally, you should GROUP BY the same fields as specified in your SELECT. This should work:
SELECT c.FullName, COUNT(l.Id)
FROM Organisations c
JOIN UsersTable u ON u.OrganisationId = c.Id
LEFT JOIN LoginsTable l ON u.Email = l.Email AND l.AttemptTime > "2019-10-01" AND l.AttemptTime < "2019-11-01" AND l.Success = 1
GROUP BY c.FullName
ORDER BY c.FullName
I found 2 issues here:
your group by column is not listed on your column
date condition is using double quotes.
try below query.
SELECT c.FullName, COUNT(l.Id)
FROM LoginsTable l
LEFT JOIN UsersTable u ON u.Email = l.Email
LEFT JOIN Organisations c ON c.Id = u.OrganisationId
WHERE l.AttemptTime between '2019-10-01' AND '2019-11-01' AND l.Success = 1
GROUP BY c.FullName
ORDER BY c.FullName ASC;
As Roman Hocke said you need to use left join as below :
SELECT c.FullName, COUNT(l.Id)
FROM UsersTable u
JOIN Organisations c ON c.Id = u.OrganisationId
LEFT JOIN LoginsTable l ON u.Email = l.Email
WHERE l.AttemptTime > "2019-10-01" AND l.AttemptTime < "2019-11-01" AND l.Success = 1
GROUP BY c.Name
ORDER BY c.Name ASC;
Moreover, you should fix your group by or select using the same field : SELECT c.Name or GROUP BY c.FullName ORDER BY c.FullName
EDIT : Nick's answer is the one. As he said perfectly well, you need to put your conditions in the on clause of your left join.
SELECT c.FullName, COUNT(l.Id)
FROM UsersTable u
JOIN Organisations c ON c.Id = u.OrganisationId
LEFT JOIN LoginsTable l ON (u.Email = l.Email AND l.AttemptTime > "2019-10-01" AND l.AttemptTime < "2019-11-01" AND l.Success = 1)
GROUP BY c.FullName
ORDER BY c.FullName ASC;
SELECT
u.*,
GROUP_CONCAT(DISTINCT f.shot_id SEPARATOR ",") AS ownFavorites,
GROUP_CONCAT(DISTINCT st.shot_id SEPARATOR ",") AS ownStars,
GROUP_CONCAT(DISTINCT s.id SEPARATOR ",") AS ownShots,
( SELECT AVG(p.count)
FROM points p
LEFT JOIN shots s ON s.user_id = **U.ID** AND p.shot_id = s.id
WHERE date >= DATE_SUB(CURDATE(),INTERVAL 2 DAY)
) AS attention,
( SELECT SUM(p.count)
FROM points p
LEFT JOIN shots s ON s.user_id = **U.ID** AND s.id = p.shot_id
) AS popularity
FROM users u
LEFT OUTER JOIN shots s ON s.user_id = u.id
LEFT OUTER JOIN favorites f ON f.user_id = u.id
LEFT OUTER JOIN stars st ON st.user_id = u.id
WHERE u.username = ?;
I got two subselects which use the parameter u.id (marked in the query). If i do the sql like this it will generate somthing like that:
#1054 - Unknown column 'u.id' in 'on clause'
Means, the u.id id is NOT defined in the SubSelects. But in the MainSelect I choose from the users table, where u.id exists.
To my question: Is there a way to pass the selected u.id value to the Subselects with common sql?
Don't forget GROUP BY in the subqueries:
SELECT
u.*,
COALECSE(a.average, 0) attention,
COALESCE(p.total, 0) popular,
GROUP_CONCAT(DISTINCT f.shot_id) AS ownFavorites,
GROUP_CONCAT(DISTINCT st.shot_id SEPARATOR ",") AS ownStars,
GROUP_CONCAT(DISTINCT s.id SEPARATOR ",") AS ownShots
FROM
users u
LEFT JOIN
(
SELECT
s.user_id,
AVG(p.count) average
FROM
shots s
JOIN
points p
ON s.id = p.shot_id
WHERE
s.date >+ CURRENT_DATE - INTERVAL 2 DAY
GROUP BY s.user_id
) a
ON u.id = a.user_id
LEFT JOIN
(
SELECT
s.user_id,
SUM(p.count) total
FROM
shots s
JOIN
points p
ON s.id = p.shot_id
GROUP BY s.user_id
) p
ON u.id = p.user_id
LEFT OUTER JOIN shots s ON s.user_id = u.id
LEFT OUTER JOIN favorites f ON f.user_id = u.id
LEFT OUTER JOIN stars st ON st.user_id = u.id
WHERE u.username = 'user'
Seems like this may work. The select doesn't have knowledge of the of the users table the way you had it. I believe this would have knowledge of Users.
SELECT
u.*,
GROUP_CONCAT(DISTINCT f.shot_id SEPARATOR ",") AS ownFavorites,
GROUP_CONCAT(DISTINCT st.shot_id SEPARATOR ",") AS ownStars,
GROUP_CONCAT(DISTINCT s.id SEPARATOR ",") AS ownShots,
A.Attention, P.Popularity
FROM users u
LEFT OUTER JOIN shots s ON s.user_id = u.id
LEFT OUTER JOIN favorites f ON f.user_id = u.id
LEFT OUTER JOIN stars st ON st.user_id = u.id
LEFT OUTER JOIN
( SELECT AVG(p.count) attention
FROM points p
LEFT JOIN shots s ON s.user_id = **U.ID** AND p.shot_id = s.id
WHERE date >= DATE_SUB(CURDATE(),INTERVAL 2 DAY)
) AS A,
( SELECT SUM(p.count) popularity
FROM points p
LEFT JOIN shots s ON s.user_id = **U.ID** AND s.id = p.shot_id
) AS P
WHERE u.username = ?;
Try turning the selects into a subselect join.
FROM users u
LEFT OUTER JOIN shots s ON s.user_id = u.id
LEFT OUTER JOIN favorites f ON f.user_id = u.id
LEFT OUTER JOIN stars st ON st.user_id = u.id
LEFT OUTER JOIN ( SELECT AVG(p.count) AverageOfP, p.shot_id
FROM points p
WHERE date >= DATE_SUB(CURDATE(),INTERVAL 2 DAY)
) p ON p.shot_id = s.id
LEFT OUTER JOIN ( SELECT SUM(p.count) SumOfP, p.shot_id
FROM points p
) p2 ON p2.shot_id = s.id
The s table is already joined to u and should be good. Then in your select you can just select AverageOfP and SumOfP.
SELECT s.*,
u.username,
u.fullname,
c.title AS ctitle,
c.description AS cdescription,
sa.attention,
sp.popularity,
COUNT(DISTINCT f.id) AS favorites,
COUNT(DISTINCT st.id) AS stars,
COUNT(DISTINCT v.id) AS views
FROM shots s
INNER JOIN users u ON u.id = s.user_id
INNER JOIN categories c ON c.id = s.cat_id
LEFT OUTER JOIN(
SELECT shot_id, round(AVG(count),2) AS attention
FROM points
WHERE date > DATE_SUB(CURDATE(),INTERVAL 2 DAY)
GROUP BY shot_id
) sa ON sa.shot_id = s.id
LEFT OUTER JOIN(
SELECT shot_id, SUM(count) AS popularity
FROM points
GROUP BY shot_id
) sp ON sp.shot_id = s.id
LEFT OUTER JOIN favorites f ON f.shot_id = s.id
LEFT OUTER JOIN stars st ON st.shot_id = s.id
LEFT OUTER JOIN views v ON v.shot_id = s.id
**WHERE s.library = 1 AND sa.attention > 40
ORDER BY sa.attention DESC
LIMIT 0,50**
GROUP BY s.id
I can't use the sa.attention in a condition and for ordering. Why?
(I removed the marked part, and the query works!)
What do I have to change in my Query? And if you could give a explanation for it, that would be very nice!
You are negating your OUTER JOIN by putting that in your WHERE criteria. Move it to your JOIN and you'll get your NULL records back:
SELECT s.*,
u.username,
u.fullname,
c.title AS ctitle,
c.description AS cdescription,
sa.attention,
sp.popularity,
COUNT(DISTINCT f.id) AS favorites,
COUNT(DISTINCT st.id) AS stars,
COUNT(DISTINCT v.id) AS views
FROM shots s
INNER JOIN users u ON u.id = s.user_id
INNER JOIN categories c ON c.id = s.cat_id
LEFT OUTER JOIN(
SELECT shot_id, round(AVG(count),2) AS attention
FROM points
WHERE date > DATE_SUB(CURDATE(),INTERVAL 2 DAY)
GROUP BY shot_id
) sa ON sa.shot_id = s.id AND sa.attention > 40
LEFT OUTER JOIN(
SELECT shot_id, SUM(count) AS popularity
FROM points
GROUP BY shot_id
) sp ON sp.shot_id = s.id
LEFT OUTER JOIN favorites f ON f.shot_id = s.id
LEFT OUTER JOIN stars st ON st.shot_id = s.id
LEFT OUTER JOIN views v ON v.shot_id = s.id
WHERE s.library = 1
GROUP BY s.id
ORDER BY sa.attention DESC
LIMIT 0,50
A second note, GROUP BY cannot go at the end. I moved that to the correct spot as well.
I have two tables, users and contestants. I'm trying to select the max contestant ID that has a profile picture(which is on the user table)
Heres my terrible SQL:
SELECT u.thumbnail, u.id FROM users AS u
INNER JOIN
(
SELECT c.id, c.user_id FROM contestants AS c
WHERE u.id = c.users_id
AND c.id = (select max(c.id))
) WHERE u.thumbnail IS NOT NULL
The error currently is: #1248 - Every derived table must have its own alias.
This confuses me since Users has an alias of u, and contestants has an alias of c..
What am I doing wrong here? I'm guessing a lot so some help would be really appreciated!
Whenever you are performing a join operation, you are actually joining two table. The subquery you wrote here, for instance, is working as a separate table. Hence, you have to use an alias to this table. That's the reason behind your error message.
Your query:
SELECT u.thumbnail, u.id FROM users AS u
INNER JOIN
(
SELECT c.id, c.user_id FROM contestants AS c
WHERE u.id = c.users_id
AND c.id = (select max(c.id))
) WHERE u.thumbnail IS NOT NULL
It should contain an alias for the subquery:
SELECT c.id, c.user_id FROM contestants AS c
WHERE u.id = c.users_id
AND c.id = (select max(c.id))
Let's say, it's T.
So, your query now becomes:
SELECT u.thumbnail, u.id FROM users AS u
INNER JOIN
(
SELECT c.id, c.user_id FROM contestants AS c
WHERE u.id = c.users_id
AND c.id = (select max(c.id))
) AS T
WHERE u.thumbnail IS NOT NULL
But what you are trying to achieve, can actually be done in a neater way:
SELECT u.thumbnail, u.id, max(c.id),
FROM users as u
LEFT JOIN contestants as c
on u.id = c.user_id
WHERE u.thumbnail IS NOT NULL
Why make all the fuss when you have a better and neater approach at your disposal?
try this:
SELECT u.thumbnail, u.id
FROM users AS u
INNER JOIN
(
SELECT c.id, c.user_id FROM contestants AS c
WHERE u.id = c.users_id
AND c.id = (select max(c.id))
)A
WHERE u.thumbnail IS NOT NULL
i think this should be simple,
SELECT u.thumbnail, u.id
FROM users u
INNER JOIN contestants c
ON u.id = c.users_id
WHERE u.thumbnail IS NOT NULL
ORDER BY c.id DESC
LIMIT 1
This is very simple.
SELECT user.thumbnail, user.id
FROM users user
INNER JOIN contestants cont ON cont.id = cont.users_id
WHERE cont.thumbnail IS NOT NULL
ORDER BY user.id DESC
How would I do following in MySQL:
I have 3 tables:
user: id
communication: id, creation_date
user_communication: user_id, communication_id
Now I want to select all users that have had no communication since a given date.
Following is what I have now, but I'm stuck on how to get what I described above.
SELECT DISTINCT u.id FROM user u
LEFT JOIN user_communication uc ON uc.user_id = u.id
LEFT JOIN communication c ON c.id = uc.communication_id
WHERE c.creation_date < '2013-8-1';
The where condition is undoing the left join. The initial solution would be to move it to the on clause:
SELECT DISTINCT u.id FROM user u
LEFT JOIN user_communication uc ON uc.user_id = u.id
LEFT JOIN communication c ON c.id = uc.communication_id and c.creation_date < '2013-8-1';
But this doesn't do what you want. This retrieves all records. If you had a creation date field in the select clause, it would be NULL when there is record before that date.
For no communication since that date, you can do a "double" negative" query. Look for records that are since that date, and return the mismatches:
SELECT DISTINCT u.id
FROM user u LEFT JOIN
user_communication uc
ON uc.user_id = u.id LEFT JOIN
communication c
ON c.id = uc.communication_id and c.creation_date >= '2013-08-01'
WHERE c.creation_date is NULL;
EDIT:
I see. The problem is a little more subtle than my answer above. Each user has multiple communications, so none can be later. The following query tests this by grouping by u.id and then checking that there are no non-NULL values from the above join:
SELECT u.id
FROM user u LEFT JOIN
user_communication uc
ON uc.user_id = u.id LEFT JOIN
communication c
ON c.id = uc.communication_id and c.creation_date >= '2012-08-01'
group by u.id
having min(c.creation_date is null) = 1;
SELECT DISTINCT u.id FROM user u
LEFT JOIN user_communication uc ON uc.user_id = u.id
LEFT JOIN (SELECT * FROM communication WHERE creation_date < '2013-8-1') c
ON c.id = uc.communication_id
WHERE c.id is NULL;
After some research and help I have following query, which seems to work:
SELECT DISTINCT(u.id)
FROM user u
WHERE (SELECT coalesce(max(c.creation_date), '1900-01-01 00:00:00') last_creation_date
FROM user inneru
LEFT JOIN user_communication uc ON uc.user_id = inneru.id
LEFT JOIN communication c ON c.id = uc.communication_id
WHERE inneru.id = u.id) < '2012-08-01'
SQLFiddle: http://sqlfiddle.com/#!2/5dfad/10