Q:

Storing database structure

Is there some tool that can store for me the database structure, say in some xml file or something like that. 
And later from the code it can generate for me the sql query for this database creation ? 
Currently I am working with MySQL , but it probably does not matter .  
Just I not want to maintain my self all those things. 

A:

In my experience I have used MySQL Workbench to take care of issues like this.  If you download Workbench (assuming you don't have it already) from http://wb.mysql.com/ you will have the option to "Create an EER diagram from an existing database."  This will create an EER diagram which is a good visual presentation of the database with which you are working.  The .mwb file that you can then save can be loaded and then "forward engineered" into local/external database. 
Mysqldump is another alternative to use at the command line.  It will, by default, dump out the entire schema structure and contained data.  However, if you are just looking for database structure including views and routines and you do not care about the data itself then you need to throw some extra parameters into the command. 
In my experience Mysqldump is quick and easy whereas EER diagrams are easier to share with others and then forward engineer back onto other DBs from the Workbench application. 
EDIT
You should note that just because you export the database create table queries to a .sql file or .mwb file that you can't just copy and paste the text into another platform (Microsoft SQL, Oracle, etc) and expect it to work.  Syntax across different versions of SQL is (obviously) different.