在php + mysql中重新排列最新的对话

Question

we have building a chat application using php and mysql and our table structure looks like this

converstation_table_name

id
conversation_id
created_at
user_1
user_2

messages

sender
reciever
message
created_at
conversation_id

here are the values in both tables

conversation_table_name

id | con_id(shortname) | created_at | user_1 | user_2 |
 1 | 123132            |   now      |   1    |    5   |
 2 | 123133            |   now      |   1    |    3   |
 3 | 123134            |   now      |   1    |    4   |
 4 | 123135            |   now      |   1    |    2   |     

messages

sender | reciever | message | created_at | conversation_id |
     1 |    3     |   abc   |   now      |     123133      |
     3 |    1     |   cee   |   now      |     123133      |
     1 |    2     |   1411  |   now      |     123135      |
     1 |    5     |   1-5   |   now      |     123132      |

now we want to arrange the output something like this

123132
between 1 - 5
123135
between 1 - 2
123133
between 1 - 3

how to go about it, in short we want to make the latest message in user conversation to appear on top, just like facebook does with it's messaging system, how to go about it, we are still looking for a working answer

Answer 1

Can be introduced new field viewed or seen with datetime field. On visiting message update the field. So can be used order by that field and you will have the viewed time.