What do you need this all for?

What a strange idea you have to create a table for each session?
What for do you need a table if you already have got a session?
What do you want to record into this table? Is it impossible to record this into a session?

You’ve invented something strange.
When I see some complicated construction which is not typical for a PHP-beginner I have a doubt concerning conceiving of such actions. And I’m nearly always right.
What type of data is it and why are they difficult to handle?

Look up necessary function in the documentation. Although base is synonymic to constancy and session is temporary by definition. It’s a strange combination…

base is synonymic to constancy

But at the same time it has temporary tables.

I didn’t realize the problem.
Is such solution right:
session_start(); // first (!) session start
$PHPSESSID=session_id();
echo $PHPSESSID; // there shouldn’t be any error here. And which error could it be?
//I haven’t checked it but it shouldn’t cause any troubles. It doesn’t matter if you start it for the first time or not, everything should work properly.

Using session code for each table should be scaring. Aren’t you afraid that tables will multiply and there will be LOTS of them and it won’t be helped  It’s not always easy to trace deletion. Though it’s up to you to decide what to do and how.

If you need each session’s data and you are eager to save them in the base it could be a solution to place them all into one table in which will a field will be to save your session and all its data.

This will help you for sure if you intended to have similar tables’ structure (when you were going to multiply lots of tables)!