0 - 4 of 4 tags for variables

Hi -
Can someone help me understand if the values in the variable change when the values in the source changes?
Sample Tbl1 Data:
Sample Tbl2 Data:
Fld1     Fld_X
1         ABC
2         XYZ
To explain it better, here is the sample SQL:

I am a TD newcomer and still figuring out details. 
I came across below piece of code that caught my attention.

Good Morning All,
I've just changed roles. I've got about 4 years experience with MS SQL Server (T-SQL) and my new role uses Teradata.

The commonly known technique to pass parameters to SQL statements at the system or session level utilizes tables (permanent or global temporary tables).
In this blog post, I'll show better performing techniques for system and user level variables using views and QueryBanding.
These solutions are based on TD13, but can also be used pre-TD13, although performance might be worse.