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Groupwise Max SQL Query Problem

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.

Beceriler: Veri Tabanı Yönetimi, Veritabanı Programlama, MySQL, SQL

Daha fazlasını gör: sql query tree structure records, asterisk call forward database sql query, sql query child child, sql select max row per group, mysql select row with max value group by, select row with max value in one column, mysql group by max other column, mysql max group by, sql select max group by, groupwise maximum, mysql select max value for each group, mysql, sql, database administration, database programming, sql query tree structure, sql query tree children, getafreelancer message sql query help needed, specialise sql query, sql query find number child elements

İşveren Hakkında:
( 6 değerlendirme ) Bangkok, Thailand

Proje NO: #17161183

Seçilen:

ahmeddarwish123

Hi haha. Interesting. Considering your job description, my thought is the following... 1. you want to get the latest row for each data source , that includes several ratings. 2. so, you have to do group by operati Daha Fazla

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4.2

Bu iş için 15 freelancer ortalamada $26 teklif veriyor

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5.7
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 Daha Fazla

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(7 Değerlendirme)
5.5
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

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5.4
Tamalnaskar6

Hello , I'm Tamal, I have 6 years exp. I'm individual work on freelancer. So, I can finish it within short time. My portfolio is : [login to view URL] My Sample: E-Commerce Projects (Online Shopping) ------ Daha Fazla

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4.1
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 Daha Fazla

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sreenivas2903

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

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ukgolang

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

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mountian1997

Hi, dear! I saw your proposal. I feel confidence about your project. I am a excellent web developer. I can perfectly do your job. If you give me chance, you have good result in short time. I hope you will hire m Daha Fazla

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in %bids___i_period_sub_35% gün içinde10%project_currencyDetails_sign_sub_37% %project_currencyDetails_code_sub_38%
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0.0
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!

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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

in %bids___i_period_sub_35% gün içinde25%project_currencyDetails_sign_sub_37% %project_currencyDetails_code_sub_38%
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Ko915

".....Select SUM([login to view URL]) From main_table AS m Left Join data_item AS d On m.data_item_id = [login to view URL] Order By [login to view URL] Desc ......" Dear sir I am a professional database developer. If you want I can do using teamv Daha Fazla

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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, Daha Fazla

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