Query Expression?

What is function using in Select statement of SQL ? Please help me ! Thanks !

I don’t understand your question. Could you post your query?

EX : Select ProductName from Products
Where ProductID ==value;
Select Statement of SQL using function …???

SELECT is not a function.
http://dev.mysql.com/doc/refman/5.5/en/select.html

Thanks, but how it perform ?

Maybe we should start from the beginning, are you asking how to run that query from your code or are you asking what that query does when it hits SQL server? Such as the underlying processes that take place.

These are extremely simple knowledge, in the network has a lot of documentation on how to use and access the data.You can find and read them. Because these are the basics