如何将方括号括起到已在T-SQL中设置为一个变量值的变量？

I got a script from the Net that computes the usage of datafiles and transaction log files from a certain SQL Server instance. The script works fine if there is not database name with whitespace or is not too long. However, if the database name has whitespace or is too long, I get the error message "Msg 911, Level 16, State 1, Line 1 Could not locate entry in sysdatabases for database 'Test'. No entry found with that name. Make sure that the name is entered correctly." In the sample error message, the 'Test' has the full database name of "Test DB" which has a whitespace. Please see the code below:I got a script from the Net that computes the u