IF NOT EXISTS INSERT, ELSE UPDATE -- Is it possible?

[JREAM]

Hey, Im wondering if you can do this in SQL. I have searched google and can't find what I'm looking for to explain it to me.

Is this possible? What am I doing wrong?
Or is this something I should do through PHP with multiple queries?

Basically it's a conditional statement.
These are fake values, Im just trying to learn if it can be done

    IF 
    NOT EXISTS 
        (
        SELECT user_id, bot_id 
        FROM tmp_battles 
 
        WHERE user_id = 1 
        AND bot_id = 5
        ) 
 
    THEN 
 
        INSERT INTO tmp_battles 
        SET  
        user_id = 1,
        bot_id = 2
 
 
 
    ELSE
 
        UPDATE tmp_battles
        SET
        user_id = 1,
        bot_id = 55,
 
        WHERE user_id = 10
        AND bot_id = 55
 
    END IF

Or what about something like this:

 IF 
   (SELECT COUNT(*) FROM items WHERE id = 1) > 10
THEN
    DO SOMETHING
ELSE
   DO SOMETHING ELSE

[r937]

yes, it can be done

check in the mysql manual for the INSERT statement with ON DUPLICATE KEY UPDATE clause

[JREAM]

Thank you for reply Rudy. I am looking at the ON DUPLICATE KEY right now.
My question I suppose is,

With an AUTO_INCREMENT column named id as my PRIMARY KEY
This probably will never have a duplicate.

Is there a way to check if there is a duplicated of assign_bot and assign_user?

            INSERT INTO tmp_battles
            SET 
            `assign_bot` = '$bot[id]',
            `assign_user` = '{$sess->get('userID')}',
            `battle_hp` = '$bot[hp]'
 
            ON DUPLICATE KEY 
                UPDATE `battle_hp` = '$bot[hp]'

[guido2004]

Add another unique key (assing_bot + assign_user) to the table.