I have this query as my main query, I use all the records from the members table, and selected columns from comments and chat_box.
SELECT members.*,
a.commenter_id,
b.user_id,
a.comcount,
b.chatcount
FROM members
LEFT JOIN (SELECT commenter_id,
Count(*) comCount
FROM comments
GROUP BY commenter_id) a
ON members.id = a.commenter_id
LEFT JOIN (SELECT user_id,
Count(*) chatCount
FROM chat_box
GROUP BY user_id) b
ON members.id = b.user_id
WHERE members.id = '290'
I would like to add this query to the above
SELECT Count(friend_id) AS totFriend,
friend_id AS fi,
logged_user_id AS user,
friend_accepted AS fa
FROM member_friends
WHERE logged_user_id = '1'
AND friend_id = '290'
Is it possible to add this to the mix without causing any errors? I have tried it myself but I maybe just putting my self in deeper problems. If it is possible could someone assist me in doing so, thank you :).
If you have a way to join the last query to your members table, then you should be able to use:
SELECT members.*,
a.commenter_id,
b.user_id,
a.comcount,
b.chatcount,
c.totFriend
FROM members
LEFT JOIN
(
SELECT commenter_id,
Count(*) comCount
FROM comments
GROUP BY commenter_id
) a
ON members.id = a.commenter_id
LEFT JOIN
(
SELECT user_id,
Count(*) chatCount
FROM chat_box
GROUP BY user_id
) b
ON members.id = b.user_id
LEFT JOIN
(
SELECT Count(friend_id) AS totFriend,
friend_id AS fi,
logged_user_id AS user,
friend_accepted AS fa
FROM member_friends
WHERE logged_user_id = '1'
AND friend_id = '290'
) c
on members.id = c.friend_id
WHERE members.id = '290'
Related
I have a query with one LEFT JOIN that works fine. When I add a second LEFT JOIN to a table with multiple records per field in the first table, however, I am getting the product of the results in the two tables ie books x publishers returned. How can I prevent this from happening?
SELECT a.*,b.*,p.*, group_concat(b.id as `bids`)
FROM authors `a`
LEFT JOIN books `b`
ON b.authorid = a.id
LEFT JOIN publishers `p`
on p.authorid = a.id
GROUP by a.id
EDIT:
Figured it out. The way to do this is to use subqueries as in this answer:
SELECT u.id
, u.account_balance
, g.grocery_visits
, f.fishmarket_visits
FROM users u
LEFT JOIN (
SELECT user_id, count(*) AS grocery_visits
FROM grocery
GROUP BY user_id
) g ON g.user_id = u.id
LEFT JOIN (
SELECT user_id, count(*) AS fishmarket_visits
FROM fishmarket
GROUP BY user_id
) f ON f.user_id = u.id
ORDER BY u.id;
If you do multiple LEFT Joins, your query will return a cartesian product of the results. To avoid this and get only one copy of fields you desire, do a subquery for each table you wish to join as below. Hope this helps someone in the future.
SELECT u.id
, u.account_balance
, g.grocery_visits
, f.fishmarket_visits
FROM users u
LEFT JOIN (
SELECT user_id, count(*) AS grocery_visits
FROM grocery
GROUP BY user_id
) g ON g.user_id = u.id
LEFT JOIN (
SELECT user_id, count(*) AS fishmarket_visits
FROM fishmarket
GROUP BY user_id
) f ON f.user_id = u.id
ORDER BY u.id;
I have 3 tables "maintenances", "cars", "users" . I want to select all data from table maintenance with a distinct car_id and the last record for each distinct (based on max maintenance_date)
SELECT
m. * , u.username, c.Model, c.Make, c.License, c.Milage, COUNT( m.process_id ) AS count_nr
FROM
maintenances AS m
LEFT JOIN users AS u ON u.id = m.user_id
LEFT JOIN cars AS c ON c.id = m.car_id
WHERE
maintenance_date = (SELECT MAX(maintenance_date) FROM maintenances WHERE car_id = m.car_id)
The problem is that this query returns only one record which has the max date from all records. I want all records (distinct car_id and from records with the same car_id to display only values for max(maintenance_date))
This is your query:
SELECT m. * , u.username, c.Model, c.Make, c.License, c.Milage, COUNT( m.process_id ) AS count_nr
----------------------------------------------------------------^
FROM maintenances AS m LEFT JOIN
users AS u
ON u.id = m.user_id LEFT JOIN
cars AS c
ON c.id = m.car_id
WHERE maintenance_date = (SELECT MAX(maintenance_date) FROM maintenances WHERE car_id = m.car_id);
It is an aggregation query. Without a group by, only one row is returned (all the rows are in one group). So, add the group by:
SELECT m. * , u.username, c.Model, c.Make, c.License, c.Milage, COUNT( m.process_id ) AS count_nr
FROM maintenances AS m LEFT JOIN
users AS u
ON u.id = m.user_id LEFT JOIN
cars AS c
ON c.id = m.car_id
WHERE maintenance_date = (SELECT MAX(m2.maintenance_date) FROM maintenances m2 WHERE m2.car_id = m.car_id);
GROUP BY c.id
I also fixed the correlation statement, to be clear that it is correlated to the outer query.
add GROUP BY u.username .
WHERE
maintenance_date = (SELECT MAX(maintenance_date) FROM maintenances WHERE car_id = m.car_id)
GROUP BY u.username
Getting multiple records from table with subquery joins
SELECT
COUNT(*) AS total_count,
(SELECT
chat_box.user_id,
chat_box.message,
members.id,
members.display_name
FROM chat_box INNER JOIN members
ON chat_box.user_id = members.id
ORDER BY chat_id DESC LIMIT 1),
(SELECT COUNT(DISTINCT user_id) FROM chat_box) AS users_count
FROM chat_box
This is what I have so far, I want to get the members.display_name from the inner join where the chat_box.user_id = members.id as an output along aside the chat_box.message and save members.display_name and chat_box.message to a variable. Any help is appreciated.
It is not exactly clear what you are trying to do, but it seems like you could use something like this:
select u.user_id,
u.message,
u.id,
u.display_name,
cb1.total_count,
cb1.users_count
from
(
SELECT cb.user_id ,
cb.message,
m.id,
m.display_name
FROM chat_box cb
INNER JOIN members m
ON cb.user_id = m.id
) u
CROSS JOIN
(
select COUNT(*) AS total_count,
COUNT(DISTINCT user_id) AS users_count
FROM chat_box
) cb1
I have the following query, in which I used JOINs. It says:
unknown column m.bv ..
Could you please take a look and tell me what I'm doing wrong?
$query4 = 'SELECT u.*, SUM(c.ts) AS total_sum1, SUM(m.bv) AS total_sum
FROM users u
LEFT JOIN
(SELECT user_id ,SUM(points) AS ts FROM coupon GROUP BY user_id) c
ON u.user_id=c.user_id
LEFT JOIN
(SELECT user_id ,SUM(points) AS bv FROM matching GROUP BY user_id) r
ON u.user_id=m.user_id
where u.user_id="'.$_SESSION['user_name'].'"
GROUP BY u.user_id';
You are selecting SUM(points) AS bv from the table with the alias r, there is no tables with the alias m. So that it has to be r.bv instead like so:
SELECT
u.*,
SUM(c.ts) AS total_sum1,
SUM(r.bv) AS total_sum
FROM users u
LEFT JOIN
(
SELECT
user_id,
SUM(points) AS ts
FROM coupon
GROUP BY user_id
) c ON u.user_id=c.user_id
LEFT JOIN
(
SELECT
user_id,
SUM(points) AS bv
FROM matching
GROUP BY user_id
) r ON u.user_id = m.user_id
where u.user_id="'.$_SESSION['user_name'].'"
GROUP BY u.user_id
Replace m., with r. Look at second Join
You have aliased the derived table with r and you reference that table (twice) with m. Correct one or the other.
Since you group by user_id in the two subqueries and user_id is (I assume) the primary key of table user, you don't really need the final GROUP BY.
I would write it like this, if it was meant for all (many) users:
SELECT u.*, COALESCE(c.ts, 0) AS total_sum1, COALESCE(m.bv, 0) AS total_sum
FROM users u
LEFT JOIN
(SELECT user_id, SUM(points) AS ts FROM coupon GROUP BY user_id) c
ON u.user_id = c.user_id
LEFT JOIN
(SELECT user_id, SUM(points) AS bv FROM matching GROUP BY user_id) m
ON u.user_id = m.user_id
and like this in your (one user) case:
SELECT u.*, COALESCE(c.ts, 0) AS total_sum1, COALESCE(m.bv, 0) AS total_sum
FROM users u
LEFT JOIN
(SELECT SUM(points) AS ts FROM coupon
WHERE user_id = "'.$_SESSION['user_name'].'") c
ON TRUE
LEFT JOIN
(SELECT SUM(points) AS bv FROM matching
WHERE user_id = "'.$_SESSION['user_name'].'") m
ON TRUE
WHERE u.user_id = "'.$_SESSION['user_name'].'"
The last query can also be simplified to:
SELECT u.*,
COALESCE( (SELECT SUM(points) FROM coupon
WHERE user_id = u.user_id)
, 0) AS total_sum1,
COALESCE( (SELECT SUM(points) FROM matching
WHERE user_id = u.user_id)
, 0) AS total_sum
FROM users u
WHERE u.user_id = "'.$_SESSION['user_name'].'"
I have 3 MySQL tables namely chat_comments, chat_friends and user_details and I want to display a friend list.
My tables:
chat_comments(comment_id,comment,user_id,user_id2,date_added)
chat_friends(user_id,user_id2,approved)
user_details(user_id, mainimage_id, fullname)
To do this, I need a query that will return the needed fields (u.mainimage_id, u.fullname, b.comment, b.user_id) so I can loop through the list to display a table.
SQL so far (help from #Andriy M):
SELECT
cc.comment,
cc.date_added,
u.fullname,
u.mainimage_id
FROM
user_details u
LEFT JOIN
chat_comments cc
INNER JOIN (
SELECT
user_id,
MAX(comment_id) AS maxcomment
FROM chat_comments WHERE user_id=2020 OR user_id2=2020
GROUP BY user_id
) a ON a.user_id = cc.user_id
AND a.maxcomment = cc.comment_id
ON a.user_id = u.user_id
WHERE u.user_id IN (
SELECT user_id2
FROM chat_friends
WHERE user_id = 2020
AND approved = 1
)
The above query returns the last comment made by the logged-in user's friends in conversation not the last comment between the logged-in user and his/her friend regardless of who made it.
I would like it to return the last comment between the logged-in user and their friend individually regardless of who made it. In the chat_messages table, user_id is the sender and user_id2 is the receiver. Hope it makes sense?
Like #imm said in a comment, you need to use an outer join. In case of a left join, the user_details table should become the left side of the join, the right side being the result of your inner join of chat_comments with your a derived table. You'll also need to remove the user_id IN (…) condition from inside the a subselect and re-apply it to the user_details table. Here:
SELECT
cc.comment,
cc.date_added,
u.fullname,
u.mainimage_id
FROM
user_details u
LEFT JOIN
chat_comments cc
INNER JOIN (
SELECT
user_id,
MAX(comment_id) AS maxcomment
FROM chat_comments
GROUP BY user_id
) a ON a.user_id = cc.user_id
AND a.maxcomment = cc.comment_id
ON a.user_id = u.user_id
WHERE u.user_id IN (
SELECT user_id2
FROM chat_friends
WHERE user_id = 2020
AND approved = 1
)
;
Alternatively, you could use a right join. In this case you would just need to move the user_id IN (…) condition, similarly to the LEFT JOIN solution above, and replace the second INNER JOIN with RIGHT JOIN:
SELECT
cc.comment, cc.date_added, u.fullname, u.mainimage_id
FROM
(
SELECT user_id, MAX(comment_id) AS maxcomment
FROM chat_comments
GROUP BY user_id
) a
INNER JOIN
chat_comments cc ON
a.user_id = cc.user_id AND
a.maxcomment = cc.comment_id
RIGHT JOIN
user_details u ON
a.user_id = u.user_id
WHERE u.user_id IN (select user_id2 from chat_friends where user_id=2020 AND approved=1)