Mike01, we're past that now. It was two rouge rows in the Gender column that were making SQL unhappy. The grand mystery was that SQL was evaluating the entire column...

That sounds plausible and it's what I have been thinking of as well. The execution plan is simply different for each approach. It's different enough that, as you state, the...

Good point Jeff. In this case, I didn't have any trailing spaces but your point is well taken. LEN indeed doesn't count trailing spaces. In this file, the gender column...

Success! Yet, the mystery continues as I do not feel satisfied with WHY this happens in T-SQL.

When I ran this, in an attempt to modify the Gender column:
alter...

Ok. Just for kicks, I will move that column somewhere else, drop it, recreate it to char(1), restore, and give it a go again. Still, it doesn't make sense that...