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how to group by in subquery

  • June 18, 2013 at 6:05 am

    #150371

    I have a scenario where i have a message table, which is like this

    MessageId int primary key

    token text

    hash nvarchar(50)

    subject text

    name text

    There is a tendency for messages to be duplicated, but the hash will be unique for such messages.

    Now I page the table based on some sorting, and using standard sql server paging query.

    select * from (select ROW_NUMBER() over (order by name ASC) as RI, * from MessageTable where token = '1') as SUB WHERE SUB.RI >= 50 AND SUB.RI <= 100

    What I want to do now is that I want to choose unqiue hash messagetable rows and then do the above operation on it.

    SELECT *

    FROM MessageTable

    GROUP BY Hash

    I can't seem to get this using subquery, can somebody suggest a way for that?

    Thanks,

    Roger

  • June 18, 2013 at 8:34 am

    #1625065

    Hi and welcome to the forums. In order to help we will need a few things:

    1. Sample DDL in the form of CREATE TABLE statements

    2. Sample data in the form of INSERT INTO statements

    3. Expected results based on the sample data

    Please take a few minutes and read the first article in my signature for best practices when posting questions.

    Also, you seem to be using the text datatype. This type is deprecated and is horrible for performance. You should change to varchar(max) instead. Given the columns (subject, name and token) I doubt you need more than varchar(50) or so.

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