oracle

/*ORACLE*/
I have created table with structure as below,
create table student(sno number(2),sname varchar(20) not null,sfee number(7,2) check(sfee>1000),sloc varchar(20)not null);
I tried to add primary key after creating table as below,
alter table student add consstraint st_pk_sno primary key(sno);
But it is giving error as "INVALID DATATYPE"
please somebody help me or somebody recommend something to me.

Is that posted by accident or is that a real question? This is a HeidiSQL forum, and Oracle is not supported at all by HeidiSQL.