Dynamic Database Name and Schema/Owner assignment

I need to update a table from another table several times in succession. In order to make this script easier for开发者_如何学Python people to use, I'd like to be able to dynamically reference it. Something like this:

declare @databasename sysname
set @databasename = 'm2mdata01.dbo'

select * from @databasename.mytable

This isn't working. Any suggestions as to how I can accomplish this?

You can't use variables in the FROM clause in a SQL statement. You would have to use dynamic SQL, such as this:

declare @databasename sysname
set @databasename = 'm2mdata01.dbo'
EXEC ('select * from ' + @databasename + '.mytable')