There are many ways to create the snort database.
mysql -u MASTERUSER -pMASTERPASSWORD
mysql>create database snortdb;
mysql>grant all on snortdb.* to snortuser@localhost identified by 'snortpassword';
That will use the installed sql file to populate the default 'snortdb' database and add the proper permissions for the 'snortuser' of your choice with the 'snortpassword' of your choice.