Questions about PHP Login ideas

PHP Login Ideas Questions
Think for a while, no results, ask for ideas

The problem is as follows:
Now want to be a php+mysql chat room, to log in before entering the chat room,
A table records the user's registration information
A table to record the user's speech information


Now the question is how to output a speech with a user name

Now you can only output a statement, because after the statement is recorded to the database and then output from the database,
Do not know how to output a speech with a user name,
The way to do that is user name + speech
I do not know how the user name and speech are linked together.

Like many websites log in after the output of the comment is with the user name, do not know how to achieve, seeking ideas.

------Solution--------------------
... What's the idea? After login, the user name is saved in session.
When the output is added $_session[' UserName '; No, it's okay?

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