I am trying to store a database name in a variable:

```
DECLARE @SQLString  varchar(max)
DECLARE @DBIn  varchar(50)

SET @DBIn ='myDB'
SET @SQLString = 'USE ' + @DBIn 

select @SQLString
EXEC(@SQLString)

```

There are no errors when I execute this code but it does not actually works (the database does not change as it would if I just run a `USE [myDB]`).