I want to join two tables and return a random field from the second table because there are multiple matches when joining.
For example. I have a users table and a user_posts table. I want to select each user's id, and a random post id and the post's message that they have in the user_posts table. Each user can have multiple posts in the user_posts table.
This answer explains what I'm trying to do, but it's not working. Here's my query:
SELECT user_id, post_id, message FROM (
SELECT users.id AS user_id, user_posts.id AS post_id, message
FROM users INNER JOIN user_posts ON users.id = user_id
ORDER BY RAND()
) AS a GROUP BY user_id
For testing, I added two rows in the user_posts table for user with id of 1 but it's retrieving the same post every time.
using cross apply to get random one post and join to users to display
select u.id,RandomPostbyUser.*
from users u
cross apply (
SELECT user_posts.id AS post_id, message
FROM users u1 INNER JOIN user_posts ON u1.id = u.id
order by RAND()
LIMIT 1) RandomPostbyUser
Related
There are three tables, I would like to get the count of a user's total tweets and the count of likes his total tweets received.
I tried to combine two queries to get what I want but failed. Have looked through several previous questions but still can't figure it out.
Users table
id
name
1
User1
Tweets table
id
UserId (foreign key)
content
1
User1
hello
Likes table
id
UserId (foreign key)
TweetId (foreign key)
1
User1
hello
First query:
SELECT Users.name, Users.id, COUNT(Tweets.UserId) AS UserTweetCount FROM Users
LEFT JOIN Tweets
ON Users.id = Tweets.UserId
GROUP BY Users.id
ORDER BY UserTweetCount DESC;
Second query:
SELECT Users.name, Users.id, COUNT(Likes.UserId) AS UserTweetBeLikedCount FROM Users
LEFT JOIN Likes
ON Users.id = Likes.UserId
GROUP BY Users.id;
I tried like below but would get wrong UserTweetBeLikedCount counts. The counts would be UserTweetCount's, not UserTweetBeLikedCount's. When I ran two queries separately, it worked well. But when I combined them together, it didn't work right.
Don't know how to display the right counts. Can someone give me hints to solve this, please?
SELECT Users.name, Users.id,
COUNT(Tweets.UserId) AS UserTweetCount, COUNT(Likes.UserId) AS UserTweetBeLikedCount
FROM Users
LEFT JOIN Tweets
ON Users.id = Tweets.UserId
LEFT JOIN Likes
ON Users.id = Likes.UserId
GROUP BY Users.id
ORDER BY UserTweetCount DESC;
I recommend using correlated subqueries for this:
SELECT u.*,
(SELECT COUNT(*)
FROM Tweets t
WHERE u.id = t.UserId
) AS UserTweetCount,
(SELECT COUNT(*)
FROM Likes l
WHERE u.id = l.UserId
) AS UserLikeCount
FROM Users u
ORDER BY UserTweetCount DESC;
As a note: For performance, you want indexes on Tweets(UserId) and Likes(UserId).
I have two tables - users and login_reports.
users table have 4 columns - id, email, name, password, created_at, updated_at
login_reports table have 3 columns - id, user_id, created_at.
Every time user logins, an entry is created in login_reports.
Now I have to write a query to show login reports on admin dashoard.
The query should return rows of users having login count and last login.
Can someone help me with this.
SELECT users.id AS id, count(users.id) FROM users
INNER JOIN login_reports
ON users.id = login_reports.user_id
GROUP BY users.id
How do I get last login timestamp i.e. the last entry of that user in login_reports (created_at).
I think you want something like this
select u.id, count(r.id), max(r.created_at)
from user u
left join login_reports r on r.user_id = u.id
group by u.id
edit: thanks #tcadidot0
I used following query to solve this
SELECT users.id as id, count(login_reports.id) as login_count, login_reports.created_at as last_login FROM users LEFT JOIN (SELECT * FROM login_reports ORDER BY created_at DESC) login_reports ON users.id = login_reports.user_id
I have three tables:
table: users / columns: user_id, email, username
table: activities / columns: object, type, like_count
table: activities2 / columns: object, target_type, subject, type
The like_count in activities table has no problem and I count all of that with this query:
SELECT SUM(activities.like_count) AS likes, users.user_id, users.email, users.username
FROM activities
INNER JOIN users
ON activities.subject = users.user_id
GROUP BY user_id
But there is another count in activities table which is being inserted(NOT UPDATED) each time some other types of posts liked and I counted them by this query:
SELECT activities.subject, activities.object, COUNT(activities.type) AS likes
FROM activities
INNER JOIN activities2
ON activities.object = activities2.object AND activities2.target_type = 'parent'
WHERE activities2.type LIKE 'like_%'
GROUP BY activities2.subject
BUT the problem starts from here when I want to join them together! I want to count like_count + count of likes that inserted in that table(activities2) that contains string of 'like_' and beside this I want to join the subject(in activities table) which is related to user_id in the other table(users).
My last query is this:
SELECT users.user_id, users.email, users.username, activities.object, COUNT(activities.type)+SUM(activities.like_count) AS likes
FROM activities
INNER JOIN activities2
ON activities.object = activities2.object AND activities2.target_type = 'parent'
INNER JOIN users
ON activities.subject = users.user_id
WHERE activities2.type LIKE 'like_%'
GROUP BY users.user_id
The problem is when joining, it fetches the user information not for the one that I want.
In conclusion I want something like this:
user_id------email-----------------username----------object-------likes
2521---------a#b.com---------------abc---------------9578---------3
5484---------c#d.com---------------def---------------8547---------16
8431---------e#f.com---------------ghi---------------4584---------1
And offcourse the result is this but only likes are correct however columns of user_id, email, username that are in users table NOT!
I was wondering if you would help to fix it. I'm really tired of trying and facing to no result :(
users table data:
user_id-------------email---------------username
1-------------------a#b.com-------------abc
2-------------------c#d.com-------------def
3-------------------e#f.com-------------ghi
activities table data:
object----------type----------------like_count------subject
20--------------like_video----------0---------------1
20--------------like_photo----------0---------------2
33--------------like_music----------0---------------3
33--------------some_other_type-----5---------------6
33--------------some_other_type-----8---------------10
activities2 table data:
object------target_type-----subject-----type
20----------parent----------30----------like_video
21----------owner-----------40----------like_audio
22----------parent----------50----------something_not_start_with_like_
I want:
user_id------email-----------------username----------object-------likes
1------------a#b.com---------------abc---------------9578---------(sum of like_count + count of type which has like_ in first characters)
2------------c#d.com---------------def---------------8547---------(sum of like_count + count of type which has like_ in first characters)
3------------e#f.com---------------ghi---------------4584---------(sum of like_count + count of type which has like_ in first characters)
Consider joining the aggregate queries using derived tables and then run your addition calculation in the outer query. Also, below object column is removed from the second aggregate query's GROUP BY clause but still used in JOIN since you need summation at the subject level.
SELECT u.user_id, u.email, u.username, a.`object`, u.likes + a.likes as `total_likes`
FROM
(SELECT SUM(activities.like_count) AS likes, users.user_id, users.email, users.username
FROM activities
INNER JOIN users
ON activities.subject = users.user_id
GROUP BY user_id, users.email, users.username) u
INNER JOIN
(SELECT activities.subject, COUNT(activities.type) AS likes
FROM activities
INNER JOIN activities2
ON activities.object = activities2.object AND activities2.target_type = 'parent'
WHERE activities2.type LIKE 'like_%'
GROUP BY activities2.subject) As a
ON u.user_id = a.subject
Currently I have the following database:
Table 1: Customer_Stores
unique_id
page_address
date_added
guide_summary
user_name
cover_photo
guide_title
Table 2: Customer_Stories_Likes
story_id
likex
The 'like' column in the second table contains a 1 or a 0 to indict whether or not a user has liked a post.
What I'd like to do is join these two tables together with 'post_id' and count all of the 'likes' for all the posts based on post_id and order these by how many likes each post got. Is this possible with a single statement? or is it better to use a Count(*) to first determine how many likes each post has?
Yes, it's possible, but you don't need an inner join, because you don't actually need the posts table to do it.
SELECT post_id, count(like) AS post_likes
FROM likes
WHERE like = 1
GROUP BY post_id
ORDER BY post_likes DESC
If you need other information from the posts table as well, you could join it to a subquery that gets the like counts.
SELECT posts.*, like_count
FROM
posts LEFT JOIN
(SELECT post_id, count(like) AS like_count
FROM likes
WHERE like = 1
GROUP BY post_id) AS post_likes
ON posts.post_id = post_likes.post_id
ORDER BY like_count DESC
I used LEFT JOIN rather than INNER JOIN, you can use INNER JOIN if you don't want to include posts with no likes.
I have a table posts with columns board_id, author_id, message. I have another table users with columns id, name, avatar_url.
I need to write a query to get all of the users that have posted on a given board, with no duplicates. The query should return the full user row (id, name, avatar_url).
I've tried
SELECT DISTINCT users.*, posts.author_id
FROM users
INNER JOIN posts
ON users.id = posts.author_id
WHERE posts.board_id = [desired board ID]
but that's giving me duplicates of each user.
There is also the possibility that my query is correct and I've goofed on something elsewhere...
Here's a simple query that will get you all the rows in users with post activity w/o duplication
SELECT * FROM USERS
WHERE id IN (SELECT author_id FROM posts WHERE board_id = [desired board]
You could also use your basic syntax with a distinct on everything you need distinct, e.g.:
SELECT DISTINCT users.*
FROM users
JOIN posts ON users.id = posts.author_id
WHERE posts.board_id = [desired board ID]
Just group by the user id, like so:
SELECT users.id, MIN(users.name), MIN(users.avatar_url)
FROM users
INNER JOIN posts
ON users.id = posts.author_id
WHERE posts.board_id = [desired board ID]
GROUP BY users.id
SELECT users.id, users.name, users.avatar_url, posts.author_id
FROM users
INNER JOIN posts
ON users.id = posts.author_id
WHERE posts.board_id = [desired board ID] GROUP BY users.id
This will get all found rows and then group them by the userid so each user id will appear just once, hence each user row [who posts on the board] will appear just once.
Yet better is use with annotation not for highlighted after IN, which defense against duplicate values. That's it.