On Application Integration

I'm currently working on an integration for several applications for an organization. After some readings and discussions, i concluded that applications integration for my case can be executed for these three levels, which are:

1. Application level: this can be done in several ways like web service, or just simply put the application codes in one directory, like a portal
   
2. User Management level: use two levels of authentication using one pair of username-password used to access the root, or the home, next check if that logged-in user have the privilege to access the application listed in his home
   
3. Database level: put all the schemas in one database (this is actually because of the constraint existed in Postgresql -the DBMS used in this case). I need several application to access one type of data. To cut off data redundancies.

All in all, what i mean was, one object can be accessed in several ways by several other objects and viewed by several users in several formats.

regards.

Beside And

a friend, asks for a favor, what the query u could use to retrieve records from 2 tables that are almost the same which are different. he was saying about retrieving records besides the records that can be retrieved by inner join. that means he needs everything outside the complement of the union of the records from the two tables (am i explaining it right?). so i suggest select * from tbla, tblb where cola1 != colb1 and cola2 != colb2 and so on for the rest of the column.
and he said it wont work, because it will only retrieve rows which columns are all different. hmm he got a point there. so i called him later on that day, and feel like struck by some feeling, which archimedes first discover about liquid pressure (?), that aha feeling, i said he should use or instead of and.
the next morning, how can i be so dumb to suggest him to use and in the first place? isnt on of the first law that u learn about union, that !(a and b) == !a or !b ?
!(a or b) == !a and !b, or something like that.. (i get confused my self, HOW UNFORGIVABLE!)

~yaagitudeeehh

Transaction Logging

do not put echo or print in a database connection class at execute query function if you have a daemon which output is written in a log file.
log only the data crucial for debugging, if something should gone wrong. like transaction id, error id, and the query that caused the program to abort.
if you must write every query executed by the db server, make a cronjob to periodically backup the files, clean the space, so you could use it for somethin more useful. not that i say loggin is not useful.

test

this is suppossedly about some tricks, and tips, and technics, and whateer about IT that i picked along my way as an IT Slave