These following lines came from http://asktom.oracle.com/pls/asktom/f?p=100:11:0::::P11_QUESTION_ID:123212348063 Or you might visit http://www.orafaq.com/faq/what_is_the_difference_between_varchar_varchar2_and_char_data_types
You Asked I have a database column that shall store data always 10 characters long. Which datatype should I use for it CHAR or VARCHAR2 and What is the specific reason for using that datatype ? and we said... A CHAR datatype and VARCHAR2 datatype are stored identically (eg: the word 'WORD' stored in a CHAR(4) and a varchar2(4) consume exactly the same amount of space on disk, both have leading byte counts). The difference between a CHAR and a VARCHAR is that a CHAR(n) will ALWAYS be N bytes long, it will be blank padded upon insert to ensure this. A varchar2(n) on the other hand will be 1 to N bytes long, it will NOT be blank padded. Using a CHAR on a varying width field can be a pain due to the search semantics of CHAR. Consider the following examples: ops$tk...@8i> create table t ( x char(10) ); Table created. ops$tk...@8i> insert into t values ( 'Hello' ); 1 row created. ops$tk...@8i> select * from t where x = 'Hello'; X ---------- Hello ops$tk...@8i> variable y varchar2(25) ops$tk...@8i> exec :y := 'Hello' PL/SQL procedure successfully completed. ops$tk...@8i> select * from t where x = :y; no rows selected ops$tk...@8i> select * from t where x = rpad(:y,10); X ---------- Hello Notice how when doing the search with a varchar2 variable (almost every tool in the world uses this type), we have to rpad() it to get a hit. If the field is in fact ALWAYS 10 bytes long, using a CHAR will not hurt -- HOWEVER, it will not help either. The only time I personally use a CHAR type is for CHAR(1). And that is only because its faster to type char(1) then varchar2(1) -- it offers no advantages. ________________________________ From: Roberd Wilson <[email protected]> To: [email protected] Sent: Thursday, August 13, 2009 11:30:40 AM Subject: [indo-oracle] tanya beda tipe data varchar dengan varchar2 dear all, mau tanya bedanya antara tipe data varchar dan varchar2 di database oracle apa ya?? thanks be4.. [Non-text portions of this message have been removed] [Non-text portions of this message have been removed]
