I have three queries gives me result individually correct but my requirement is i need all result in single query only so how should i proceed?
select * from user_post_like
inner join user_post on user_post_like.postID = user_post.postID
inner join Users on Users.userID=user_post_like.userID
where (user_post.poster='$uid' AND user_post_like.userID!='$uid')
ORDER BY likeID DESC;
select * from user_post_comment
inner join user_post on user_post_comment.postID = user_post.postID
inner join Users on Users.userID=user_post_comment.commenter
where (user_post.poster='$uid' AND user_post_comment.commenter!='$uid')
ORDER BY commentID DESC;
select * from user_post_share
inner join user_post on user_post_share.postID = user_post.postID
inner join Users on Users.userID=user_post_share.Share_user_id
where (user_post.poster='$uid' AND user_post_share.Share_user_id!='$uid')
ORDER BY shareID DESC;
Since you're joining the tables anyway, you can put columns from all in your select - and keep your statement readable. If you have duplicate column names (from different tables) you may need to aggregate them with functions and group by.
SELECT s.*, p.*, u.*
FROM user_post_share s
INNER JOIN user_post p ON s.postID = p.postID
INNER JOIN Users u ON u.userID = p.poster
WHERE (p.poster='$uid' AND s.Share_user_id != '$uid')
ORDER BY shareID DESC
try sumthing like this
select * from user_post_like,user_post_comment,user_post_share <inner joins> <where conditions>
Related
I have the following SQL query which returns 2 results which are the same only different by a where clause.
I would like to have them combined and group them under the user names. At the moment the two results are displayed but the results are not fully combined and the users are shown twice because of the two select statements.
How can I combine the two to create a single result.
The SQL query is as follows
SELECT
COUNT (asings.user_id),
post_status.status_id as status_id,
users.name,
users.id as user_id
from asigns
LEFT JOIN
post_status on asigns.post_id = post_status.post_id
RIGHT JOIN
users on asigns.user_id = users.id
WHERE
post_status.status_id = 2
GROUP BY users.id
UNION
SELECT
COUNT(asigns.user_id),
post_status.status_id as status_id,
users.name,
users.id from asigns
LEFT JOIN
post_status on asigns.post_id = post_status.post_id
RIGHT JOIN
users on asigns.user_id = users.id
WHERE
post_status.status_id = 3
GROUP BY users.id
See in this photo the usernames are appearing twice, what I want is to join the two username, and move count as two different columns depending on the status_id
How can I solve this. Thanks
You should use a single query with conditional aggregation:
SELECT
SUM(ps.status_id = 2) AS cnt_2,
SUM(ps.status_id = 3) AS cnt_3,
u.name,
u.id as user_id
FROM users u
LEFT JOIN assigns a ON a.user_id = u.id
LEFT JOIN post_status ps ON a.post_id = ps.post_id
GROUP BY u.id;
Use SELECT distinct for the union:
SELECT distinct * FROM ([FIRST SELECT] UNION [SECOND SELECT])
Or GROUP BY username
SELECT * FROM ([FIRST SELECT] UNION [SECOND SELECT]) GROUP BY username
BUT I suggest to review your both selects, if it differs just in the where clause so use where clause with the operator OR and you handle it just by one SELECT
Although your are using a LEFT and a RIGHT join and implicitly an INNER join between users and asigns, the WHERE clause transforms all the joins to INNER joins, because you are picking only the matching rows from post_status.
So, you only need INNER joins and conditional aggregation:
SELECT COALESCE(SUM(ps.status_id = 2), 0) counter_2,
COALESCE(SUM(ps.status_id = 3), 0) counter_3,
u.name,
u.id AS user_id
FROM users u
INNER JOIN asigns a ON a.user_id = u.id
INNER JOIN post_status ps ON ps.post_id = a.post_id
WHERE ps.status_id IN (2, 3)
GROUP BY u.id;
Following query shows the results I need from table pointsList (latest records per user grouped by column idMatch)
select * from pointsList p
inner join ( select idMatch, max(datePointsCalculated ) as MaxDate from pointsList group by idMatch ) tm
on p.idMatch = tm.idMatch and p.datePointsCalculated = tm.MaxDate
order by p.idMatch ASC
But now I want to also select some additional information about the user (from table users). My naive way to tackle this was by making a new inner join like this:
select * from pointsList p, users u
inner join users
on u.idUser = p.idUser
inner join ( select idMatch, max(datePointsCalculated ) as MaxDate from pointsList group by idMatch ) tm
on p.idMatch = tm.idMatch and p.datePointsCalculated = tm.MaxDate
order by p.idMatch ASC
But I get the error message "unknown column 'p.idUser' in on clause". I tried using users.idUser and pointsList.idUser and other combinations (renaming pointsList in the on-clouse) but I always get the unknown column error (pointsList.idUser really does exist). Anyone could explain what I am doing wrong? I would like to extend this query to another table as well.
Thank you in advance!
Comma , priority in FROM clause is less than JOIN priority. And your query acts as:
select * from pointsList p,
(
users u
inner join users
on u.idUser = p.idUser
inner join ( select idMatch, max(datePointsCalculated ) as MaxDate from pointsList group by idMatch ) tm
on p.idMatch = tm.idMatch and p.datePointsCalculated = tm.MaxDate
)
order by p.idMatch ASC
Of course, table pointsList AS p is not accessible within the parenthesis.
Use CROSS JOIN instead of comma:
select * from pointsList p
CROSS JOIN users u
inner join users
on u.idUser = p.idUser
inner join ( select idMatch, max(datePointsCalculated ) as MaxDate from pointsList group by idMatch ) tm
on p.idMatch = tm.idMatch and p.datePointsCalculated = tm.MaxDate
order by p.idMatch ASC
I am trying to make a query to fetch the newest car for each user:
select * from users
left join
(select cars.* from cars
where cars.userid=users.userid
order by cars.year desc limit 1) as cars
on cars.userid=users.userid
It looks like it says Unknown column "users.userid" in where clause
I tried to remove cars.userid=users.userid part, but then it only fetches 1 newest car, and sticks it on to each user.
Is there any way to accomplish what I'm after? thanks!!
For this purpose, I usually use row_number():
select *
from users u left join
(select c.* , row_number() over (partition by c.userid order by c.year desc) as seqnum
from cars c
) c
on c.userid = u.userid and c.seqnum = 1;
One option is to filter the left join with a subquery:
select * -- better enumerate the columns here
from users u
left join cars c
on c.userid = u.userid
and c.year = (select max(c1.year) from cars c1 where c1.userid = c.userid)
For performance, consider an index on car(userid, year).
Note that this might return multiple cars per user if you have duplicate (userid, year) in cars. It would be better to have a real date rather than just the year.
Maybe there are better and more efficient way to query this. Here is my solution;
select users.userid, cars.*
from users
left join cars on cars.userid = users.userid
join (SELECT userid, MAX(year) AS maxDate
FROM cars
GROUP BY userid) as sub on cars.year = sub.maxDate;
I am working with a MySQL database. I am suppose to combine three select queries, to "improve performance". Each select below is dependent on the previous ID retrieved.
So far, I've tried the following...
# multiple select from tables
select user.name, group.ID
from user as u, group as g
where u.name = <name_here>
# inner join...
select user.ID, group.ID,
from user
inner join group
on user.ID = group.ID
I need to select the user.name and group.ID based on a username param. Is there a way to query this data in a single statement?
I don't know if I understand your need, lets try:
Try to use this query:
select pGroupMatch.GroupID, ProfileData.ID
from pUserMatch
inner join pGroupMatch on pGroupMatch.GroupID = pUserMatch.GroupID
inner join ProfileData on ProfileData.id = pGroupMatch.ProfileID
where pUserMatch.username = "<username>";
Check if you can create indexes for improve your query, if you can try it:
CREATE INDEX idx_pUserMatch_01 ON pUserMatch (GroupID);
CREATE INDEX idx_pGroupMatch_01 ON pGroupMatch (ProfileID);
Please use join for your requirement. Please try below query
select t3.* from Profiles.pUserMatch t1
left join Profiles.pGroupMatch t2 ON t2.GroupID=t1.GroupID
left join Profiles.ProfileData t3 ON t3.ID=t2.ProfileID
where t1.username = "<username>";
I hope above query will help you.Please feel free to comment. Thanks.
This is the query you get by joining the tree queries you already have:
SELECT pd.*
FROM Profiles.ProfileData pd
# ... where ID = "<profile_id>", profile_id = select ProfileID from ...
INNER JOIN Profiles.pGroupMatch pm ON pd.ID = pm.ProfileID
# ... where GroupID = "<group_id>", group_id = select GroupID from ...
INNER JOIN Profiles.pUserMatch pu ON pm.GroupID = pm.GroupID
WHERE pm.username = "<username>"
I put in comments the fragments of your queries that gets converted to JOIN subclauses.
Read more about the syntax of the JOIN subclause of the SELECT statement.
You don't need foreign keys to join stuff:
select p.* from Profiles.pUserMatch u
join Profile.pGroupMatch g on u.GroupID = g.GroupID
join Profile.ProfileData p on g.ProfileID = p.ID
where u.username = ?
I'm trying to select results from two different unrelated tables, showcase and questions to appear in a feed. They should be ordered by the common column hotness which is a float value.
SELECT s.id,s.date,s.title,s.views,s.image,s.hidpi,s.width,s.description,u.display_name,u.avatar
FROM showcase AS s
INNER JOIN users AS u ON s.user_id = u.id
UNION
SELECT q.id,q.date,q.title,q.views,q.text,u.display_name,u.avatar,0,0,0
FROM questions AS q
INNER JOIN users AS u ON q.user_id = u.id
ORDER BY hotness DESC
LIMIT 10
I've tried UNION, but I have no idea how I should be using it here and get this error unknown column hotness
You need to select the value in order for the ORDER BY to recognize it:
SELECT s.id,s.date,s.title,s.views,s.image,s.hidpi,s.width,s.description,u.display_name,u.avatar, s.hotness
FROM showcase AS s
INNER JOIN users AS u ON s.user_id = u.id
UNION ALL
SELECT q.id,q.date,q.title,q.views,q.text,u.display_name,u.avatar,0,0,0, q.hotness
FROM questions AS q
INNER JOIN users AS u ON q.user_id = u.id
ORDER BY hotness DESC;
Note that I also changed the UNION to UNION ALL. Unless you intend to remove duplicates, there is no reason to incur the extra processing for doing that.
You can try this query:
SELECT r.* FROM (
SELECT s.id,s.date,s.title,s.views,s.image,s.hidpi,s.width,s.description,u.display_name,u.avatar, s.hotness
FROM showcase AS s
INNER JOIN users AS u ON s.user_id = u.id
UNION
SELECT q.id,q.date,q.title,q.views,q.text,u.display_name,u.avatar,0,0,0, q.hotness
FROM questions AS q
INNER JOIN users AS u ON q.user_id = u.id
) as r
ORDER BY r.hotness DESC
LIMIT 10
You need to merge Union result in subquery to apply Order by on the result. I also added hotness in select clause, please check I take field from good table.