SUBSTR and INSTR

How can I get "yong" using one function (i.e. with no if-block) from both "yong_at_shell.com" and "yong"? I want to use substr and instr. For example,

select substr('yong_at_shell.com', 1, instr('yong_at_shell.com', '@')-1) from dual;

gives me "yong" correctly. But

select substr('yong', 1, instr('yong', '@')-1) from dual;

returns nothing. The instr function in the above select statement won't find '@' and it returns 0. So the substr function returns a 0-length string. How can I still get "yong" using functions like these or replace, translate etc.? Please help. Thanks.

Yong Huang
Email:yong_at_shell.com Received on Thu Sep 24 1998 - 15:43:46 CDT