How to execute a bunch of queries against a particular database

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SQL-Server-2008R2

I have a .sql file which has many create table statements.But some of them are needed to be executed on one database ex:-DB1 and some on another ex:-DB2.how can i specify names of databases so that query gets fired on specified database.

I have found two options
create table DB1.dbo.Tablename(ID INT)
create table DB2.dbo.Tablename(ID INT)

and

use DB1
GO
create table dbo.Tablename(ID INT)
GO

Is there any other way so that i can assign the name of particular database to a bunch of queries once and queries get executed on that particular database?