now i'm a Oracle DBA,what should i do or how could i do ,if i wanna to be a DB developer?
i mean where could be my beginning of entering to the DB developement area?
Any replies are appreciate.

i would start by developing an application against one of the databases you're currently adminning (if that's a word)

rudy is right. You have to learn how to design a database to the needs of an application. You should learn about defining the scope of a problem with management, defining entities, work with analysts on creating ERDs, Normalization, Denormalization, you must also learn how to model for the environment your in. For example if your in a OO environment the techniques differ from traditional modeling.

thanks for ur advices first.i know u mean that practical experience is critical to a developer,however i also wanna know that what knowledge should i prepare for developement.'coz i think there is a gap betweeen admine and develope, am i right?if yes,what knowledge&methods i should grasp before i do a practical case.

first thing you should learn is entity-relationship modelling, followed by normalization

personally, i think those subject areas are MUCH more interesting than raid stripes and cluster packs

thanks! r937! And how about the PL/SQL? it's the general language for DBdeveloping?
do u think it's difficult to study by myself? i just bought a PL/SQL book.

as an oracle dba, you should already know pl/sql, but a good book can only help you

yes, pl/sql is the language to learn for oracle -- it's actually a "superset" of oracle sql

i would be very surprised, though, if your book spends a lot of time on entity-relationship modelling, which is what you should know to become a developer

Do you intend to write code or to design a good database?

If you want to write code you should know how to take a logical database design and denormalize it for performance into a physical database. Then you can write optimal code.

If you want to design a good database you have to be able to create a logical database design. Then you can create optimal physical models.

Either way you have to follow what rudy states. You have to understand data models to use them. PL/SQL is just another procedural language primarily developed to enable sequential processing of database rows.

well, thanks both! certus,i think my choice is to design a good DB and i know i should begin with E-R. Actually presently,i just a newbie,my current role is just a junior DBA,i like my work.However i'm also interested in DB developing,so decied the direction where i'll go further is important to me.
do u think it's possible that i could be a DBA and DBdeveloper? 1 person takes 2 roles.

of course it's possible

you could also do business needs analysis and project management

i know several people who do all 4 roles, as they are the only "computer person" in their particular company