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Re: sort Table for pairs
Posted by: Nickel Paulsen
Date: November 28, 2016 04:08PM

Peter Brawley Wrote:
-------------------------------------------------------
> The table is not well designed for the query you
> want. Is there even a primary key?

I have a primary key. The full table is:

abs | emp | content | date | subject |id|
--------+--------+-------------+----------+---------+--+
Nickel | Lisett | bla bla bla | 4.12.1991| invite | 1|
Tom | Nickel | bla bla bla | 3.10.1991| Hey | 2|
Lisett | Nickel | bla bla bla | 2.10.1991| Hey | 3|
Nickel | Lisett | bla bla bla | 15.9.1991| Hey | 4|
Tom | Nickel | bla bla bla | 03.9.1991| Hey | 5|
Nickel | Tom | bla bla bla | 01.9.1991| Hey | 6|

where id is a primary key. How could I redesign the table so it better fits the query? I have users who can log in the website and send messages to other users and abs=sender and emp=recipient are colums that only have usernames in them.

Peter Brawley Wrote:
-------------------------------------------------------
>
>
> select abs, emp, content, date from messages m
> join (
>   select distinct abs as a, emp as b from
> messages
>   union
>   select distinct emp as a, abs as b from
> messages
> ) p on (abs=a and emp=b) or (abs=b and emp-a)
> order by a,b,date;
>

This looks nice ans makes sense but I could not completely how the code works. There is a single "m" in line 2 behind messages and a single "p" in line 8. . When I make the mysql-query I don't get an output.

Thanks for the help anyway!

greets Nick

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November 28, 2016 06:37AM
November 28, 2016 11:10AM
Re: sort Table for pairs
November 28, 2016 04:08PM
November 28, 2016 04:55PM
November 28, 2016 08:37PM
November 29, 2016 03:04AM
November 29, 2016 10:01AM
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November 29, 2016 03:23PM
November 29, 2016 03:47PM
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November 30, 2016 06:41AM
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November 28, 2016 08:05PM


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