How the statement compiled

Question

Hi,
1) I want to know ,where the statements(Normal statement,Prepared statement,Precompiled statement) get compiled.
2) Why prepared statement call as a precompiled statement.What is meaning of "precompiled" over here.
3) What is difference between normal statement,prepared statement and callable statement.
4) The driver load .dll/api in class.forname() for windows enviroment.
Regards
Himanshu

Answer 1

1) I want to know ,where the statements(Normal
statement,Prepared statement,Precompiled statement)
get compiled.In the database server.
(At least usually. It would be theoretically possible to "compile" or pre-compile or tokenize the SQL string in the driver and send the results to the server, but I'd guess that would be an unusual driver implementation. If you want to check your driver & db implementation, take an TCP/IP trace of the communication between your application and the db server -- most likely, you will see SQL text strings going from the driver to the server to be compiled. What people usually call "compilation" in databases includes query optimization, which needs information that usually exists in the db server only.)
2) The driver load what ?.dll or api in
class.forname() for windows enviroment.?Depends on your database and the driver.
The most common drivers ("type 4" drivers) don't have any dll's, the driver is a .jar or a .zip file containing Java class files. I.e. the driver is written in Java, no native C/C++/Fortran/whatever dll binary at all. You just need the jar or zip file in your CLASSPATH.
In some drivers ("type 2"), there is a .jar or a .zip, which in turn loads one or more .dll's or other native binary code.
Check your database driver documentation and installation manuals.
For the four driver types, see http://java.sun.com/products/jdbc/driverdesc.html