diff b/n char and varcha2

Hi,
Could any one briefly explain me what is the diff b/n char and varchar2 everyone says char is fixed length varchar2 is valiable length i need meore explanation.

sql>create table a(name vachar2(20),grade char(3));
table created;
Explain me how the memory is allocated/used for the above columns

sql>insert into a values('Ganga','A');
one row created;
Though i have declared varchar2(10),char(3) entered only 5 char(string) name and one char grade . Now how the memory is used for above one row insertion.


Tks in advance

Gangu

well basically the varchar2 will use one byte per character so you will use 5 bytes there

The char(3) will use 3 bytes, whether you insert A or ABC - same storage used for both. So there is no need to use char at all really as it is literally a waste of space

Tks lot davey23uk
What i thinking was when we specify varchar2(20) it allocates 20 bytes for the column consumes all bytes whether we insert 20 char or less than 20 chars

once again Tks lot