Last reboot time in Linux

~]# last | grep re
reboot   system boot  2.6.18-348.el5   Mon Mar 25 18:35         (4+17:50)

When you login to the Linux machine - Banner is below

~]$ sudo su -

We trust you have received the usual lecture from the local System

Administrator. It usually boils down to these three things:

    #1) Respect the privacy of others.

    #2) Think before you type.

    #3) With great power comes great responsibility.

[sudo] password for ashenoy_r:

How to know the system time using command prompt

Go to Program -> Run -> cmd -> Press Enter

Execute the below command

>systeminfo | find /i "time"
System Boot Time:          3/26/2013, 12:30:09 AM
Time Zone:                 (UTC-08:00) Pacific Time (US & Canada)

Database - Things at a glance

In a well designed Database each table will have atleast one constraint - That says 2 different rows cannot contain exactly the same values for at worst all the columns or some of the columns.

These columns are called key. To know whether a column belongs or not to a key is the question of knowing if a different value in the column.

Constraints ensure quality of a Database.

Edward Codd - Relational theory of Databases

You can operate on Data sets, the very same way as you can operate on numbers and crunch the very same way as you crunch numbers.

Operations that apply to data set - Transform one or many data set into a new Data set - In the very same way when you add two numbers you get a new number

Data sets are weird kind of variables and is possibly the most important concept to understand

Database History

Why did Database come into existence?

Software Developers understood that a large part of data management could be shifted to full sub system.

Shifting done by set of Programs - DBMS

DBMS - Programs that run on a DB server that accept and process  high level command that instruct the computer which data to return.

DBMS takes care of file mangement
At the same time they ensure the consistency of logical units of work - composed of multiple changes, several users accessing and modifying the same data concurrently.