Groupwise Max SQL Query Problem

In Progress Posted 5 years ago Paid on delivery
In Progress Paid on delivery

I have a table that has following columns:

coin_id, data_item_id, rating, created_at

For each coin_id there's multiple rows from different data sources (marked with data_item_id), and rating from that data source.. but there are dozens of them. What I need is find the latest row for each data source (data_item_id) and get that row's rating. The output for example coin_id 32 should be:

rating: 69

69 is a SUM of ALL ratings from all "latest (determined by created_at column)" data sources.

If you undestand what I'm trying to say, or you have a concrete question ... bid and contact me, otherwise ..don't bother.

I won't hire somebody that thinks he can solve it (and if you know how it's not difficult) .. but rather somebody that really knows how.

Thanks.

Database Administration Database Programming MySQL SQL

Project ID: #17161183

About the project

12 proposals Remote project Active 5 years ago

12 freelancers are bidding on average $26 for this job

kgsolutions

Hi there, I think I can solve it. Let's communicate to proceed further. I am professional and highly motivated, having over 6+ years of DBA and Development work experience in the software industry with MySQL an More

$30 USD in 1 day
(11 Reviews)
5.6
softcarve

Hi, I would like to write the query to get sum of ratings across coin_id and data_item_id from different sources. Available to start now. Get in touch to discuss more. Regards, Manish

$30 USD in 1 day
(95 Reviews)
5.9
sreenivas2903

hi give me the sampledb i will prepare the query and deliver to you . i could have good experience in writing quieries

$28 USD in 1 day
(15 Reviews)
4.4
rrgamit

Dear Sir, After reading the job description I am confident that I would be a perfect fit for this position as my experience and abilities precisely match your requirements. Looking forward to hearing from you soon. T More

$25 USD in 1 day
(25 Reviews)
4.0
ukgolang

Hi, I'm an experienced programmer and Linux systems administrator. Constructing a MySQL as per your request won't be a problem.

$29 USD in 1 day
(7 Reviews)
3.3
RisingStar514

Hello How are you I read your job description carefully I have many good experience in Mysql Query I can finish your job quickly and quickly If you hire me, I will do my best and make you satisfied Thanks!

$25 USD in 1 day
(2 Reviews)
0.1
inghussein

Hello friend, I could help you with the requirement you have. I have the experience in SQL to solve the need you have. Thank you

$25 USD in 10 days
(0 Reviews)
0.0
Tamari

Hi I think I understand what you are getting at. Please tell me if I am correct. Given say you have some data like the following coin_id, data_item_id, rating, created_at 1, 1, 5, '2018-6-13 10:15' 1, 2, 6, More

$30 USD in 1 day
(0 Reviews)
0.0