varchar...problem still continues

[Anon]

hii..

Thanx for ur replies guys...but my question is not clearly understood i guess..

my question is i know we can do the 3 options given to me in reply but y do we need to do it.

i mean when it is a varchar ...a variable character so y r we specifying the maximum length.

The exisiting databases stores in records in addition to the varchar record the length of the record also.

y do they need to store the length of the record with it when they can calculate that very easily with the offset values i.e no of bytes can be determined by that.

my question is more related to database design issue...not with just the funcationality.

regards
rahul

[Anon]

Probably because it's stored in a binary file and it's faster to just say "read X amount of bytes" than to say "read one byte at a time till you come to a field delimeter." Probably more complex than that, but you get the idea. If you use a CHAR, it takes up that amount of space REGARDLESS of whether you fill it or not... so if you have a lot of empty records, you have a lot of wasted space.

[tomhath]

If you are asking "Why not allow every field to be infinite length and store whatever is inserted?"

There is some advantage to giving variables or fields a "type"; your way of saying "This is what I expect to store in the field, if you get something else it must be wrong". Sometimes you expect to store an integer, sometimes a date, sometimes a 30 character string...