Of course, it does depend on how the data stored in the table, if the data stored in the MODEL column is in UPPERCASE, then a query you specify in lowercase, will not return any rows. The UPPER function forces the passed variable to be made upper which.
I.e if the data in the table is
A. Select style, color, lot_no
Where model = upper('subaru');
B. Select style, color, lot_no
Where model = 'subaru';
Query a, will return 1 row and query b, will return no rows returned.
but when using upper....
I faced this problem earlier..
if u have a laarge table..then it would be a problem as the indexes are not used...but a full table scan...and my select query for the worst sql xecuted happens to be mine
So for that u would have to force indexes......