I get the following error message while I run the command ant CreateDb in cmd:

FATAL: password authentication failed for user "postgres"

I use windows 7, in order to fix the problem, I modified the file pg_hba.cong from

# TYPE  DATABASE        USER            CIDR-ADDRESS            METHOD

# IPv4 local connections:
host    all             all             127.0.0.1/32            md5
# IPv6 local connections:
host    all             all             ::1/128                 md5

to the following:

# TYPE  DATABASE        USER            CIDR-ADDRESS            METHOD

# IPv4 local connections:
host    all             all             127.0.0.1/32            trust
# IPv6 local connections:
host    all             all     开发者_StackOverflow中文版        ::1/128                 trust

then I use the same command but this time i get this error:

ERROR: language "plpgsql" already exists.

would someone please explain to me what the heck is wrong??

The error about the language plpgsql occurs because your script is trying to create the language but it is already available in the database. Either you should modify the script so it doesn't try to create the language, look for CREATE LANGUAGE or you could remove the language before hand from your database using DROP LANGUAGE plpgsql;

DROP EXTENSION plpgsql;

psql version 9.1.7