Initialitation in web services

hello, My Web Service accesses to a MS SQL database to store and retrieve data from it. but to store data, first I must to create programatacally the database and the tables. My question is what is the best way to do this? where is the best place to put the code which do this? In the beginning of each Web method (if the database and the tables do not exist, of course) or there is a common place to create or to initialize data, structures, systems, connections, etc.? thanks in advance.