What is the difference between these three Oracle datatypes?

• char
• varchar
• 开发者_如何学JAVAvarchar2

I understand that varchar2(10) will allocate space dynamically upto 10 bytes. char(10) will allocate 10 bytes at the beginning and fill it with junk if the actual datalength is less.

If this is correct, what does varchar(10) do?

It is all covered quite comprehensively in the Oracle documentation.

I think this explains it directly http://www.orafaq.com/faq/what_is_the_difference_between_varchar_varchar2_and_char_data_types