The specific answer to your question (at least for Oracle and
probably other databases) is that the length of the field
doesn’t matter, only the length of the data. However, this
shouldn’t be used as a determining factor concerning whether to
set the field to its maximum allowable length or not. Here are
some other issues you should consider before maxing out field
sizes. Any client tool that formats the data based on the size
of the fields will require special formatting considerations.
Oracle’s SQL*Plus for example by default displays the maximum
size of Varchar2 columns even if the data is only one character
long. Compare… create table f1 (a varchar2(4000), b
varchar2(4000)); create table f2 (a varchar2(5), b varchar2(5));
insert into f1 values ('a','b'); insert into f2 values
('a','b'); select * from f1; select * from f2; Field length
provides an additional mechanism to catch/prevent bad data. An
interface shouldn’t attempt to insert 3000 characters into a 100
character field, but if that field is defined