Return error number - postgresql

Question

I want to return error number using PostgreSQL 9.3 Version.
I referred this :-> http://www.postgresql.org/docs/9.4/static/errcodes-appendix.html
but want to know how do I return the error number.
In SQL Server 2008 R2 we just use ##ERROR..
Example:
IF ##ERROR <> 0
BEGIN
PRINT 'Error message';
RETURN(1);
END
My Question: Can we get error number in PostgreSQL like we get in SQL Server by using ##ERROR?

Answer 1

In PL/pgSQL, you must trap errors and you can raise (custom) errors. (Normal execution is stopped during an error.)
Errors in PostgreSQL has levels, error codes (SQLSTATE) and explicit names.
F.ex:
BEGIN
-- code that can potentially raise an error
EXCEPTION
WHEN division_by_zero THEN -- trap by name
-- handle division_by_zero
WHEN SQLSTATE '22012' THEN -- trap by SQLSTATE
-- handle SQLSTATE 22012
WHEN OTHERS THEN -- trap all other error
RAISE no_data; -- raise error by name
RAISE SQLSTATE '02000'; -- raise error by SQLSTATE
END