PHP Interview Question - 2

1. What is a schema? What are the limitations of a DTD?
2. How can I maintain the count of how many persons have hit my site?
3. what is difference between mysql_fetch_ array(),mysql_ fetch_row( ) and mysql_fetch_ object() please insert with example?
4. How i can make a chat page in php in simple?
5. What is the difference between echo and print statement?
6. What is differenc between mysql_connect and mysql_pconnect?
7. How i can get ip address?
8. How i will check that user is, logged in or not. i want to make it a function and i want to use in each page and after login i want to go in current page(same page. where i was working)?
9. How we know browser properties?
10. If you have to work with dates in the following format: "Tuesday, February 14, 2006 @ 10:39 am", how can you convert them to another format, that is easier to use?.
11. What is difference between copy constructor and constructor?