I didn't really understand what the problem is, but maybe this is the cause?
PHP Code:
//we will now select from the table `tutorial` where the steamid match
format(szTemp,charsmax(szTemp), "SELECT * FROM `tutorial` WHERE (`tutorial`.`nameid` = '%s')", szName)
SQL_ThreadQuery(g_SqlTuple, "register_client", szTemp, Data, 1)
According to both the comment and just logical thinking, you want to check for the SteamID here, but you're actually checking for the name.
If that's not it, could you please explain what you mean by "In the following code, the information is not saved immediately and the information of other players is added." or what the exact issue is with the code.