Oracle creates a custom serial number

Create 999;  -- Are you sure the serial number is only 3? 

Use the next value for it with: Seq_abc_taskid.nextval
Query current value by: Seq_abc_taskid.currval
For example, if you want to insert a line to ABC now, you can

Insert  into Values (1, Seq_abc_taskid.nextval,....);

 questioning

What I want is a date plus this serial number, what do I do with it?
Like 20140428002, the first 8 digits plus the last 3 digits.

 Chase Answer

Select to_char (sysdate,'yyyymmdd')| |  from dual;

Oracle creates a custom serial number