Ordering a Union but preserving distinction

[tissue901]

Im having some trouble here with getting my data to be properly gathered. What im doing is making a messaging system. You don't make messages by subject, rather its just by people. So all my messages towards someone shows up under the same thing. I need to get this data from the table and then order it by the time it was posted. The issue is i have to make 2 selects and then i cant get the date to order properly.

 

$userid_1 = sender, $userid_2 is reciever

 

What i have now, issue is it doesnt sort it by the date:

 

SELECT userid_2

FROM messages

WHERE userid_1='$dbid'

UNION

SELECT userid_1

FROM messages

WHERE userid_2='$dbid'

 

adding order by date doesnt work because the date column isnt loaded. Problem with this is you cant just do

 

SELECT userid_2 ,date

FROM messages

WHERE userid_1='$dbid'

UNION

SELECT userid_1,date

FROM messages

WHERE userid_2='$dbid'

order by date desc

 

because then the select doesnt stay distinct. Another solution could be adding the distinct property, but id only need one column to be distinct and idk if thats possible. so like SELECT (DISTINCT userid_2) date but thats not allowed. Im so confused, and i bet you are too, but basically its taking a bunch of messages, sorting it by the user and then ordering it by the date.

[fenway]

You want to order the results by date, regardless of the table of origin?

[tissue901]

What do you mean by the table origin?

[fenway]

I mean you don't care why it was found?

[tissue901]

I'm trying to find everything with certain usernames that meet a certain condition. I can get it to load it all right but i cant get it to order by the date sent, or i can get it to load all the messages that someones sent a message back and order it by the time, but i cant get it if you send the first message and they don't reply back to it.

 

 

[fenway]

but i cant get it if you send the first message and they don't reply back to it.

 

 

Sorry, I don't know what that means