I came across a table like this:
CREATE TABLE TABLE1 ( CD1 int ,CD2 varchar(16) ,CD3 varchar(21) ,CD4 decimal(14,0) ,CD5 varchar(4) ,CD6 decimal(18,2) ,CD7 AS (left([CD3],(4))) )
This table has more than 4 BILLION rows (totally unnecessary, but this is another topic).
As you can see in the last column, they use
AS (left([CD3],(4))). I think this is pretty useless, since we almost NEVER have a SELECT on this table, and here is just using space.
Isn't it better to select that field during the select when needed?