Recipe 2. Retrieving a Subset of Rows from a Table

Problem
You have a table and want to see only rows that satisfy a specific condition.

Solution
Use the WHERE clause to specify which rows to keep. For example, to view all employees assigned to department number 10:

1 select *
2   from emp
3  where deptno = 10

Discussion
The WHERE clause allows you to retrieve only rows you are interested in. If the expression in the WHERE clause is true for any row, then that row is returned.

Most vendors support common operators such as: =, <, >, <=, >=, !, <>. Additionally, you may want rows that satisfy multiple conditions; this can be done by specifying AND, OR, and parenthesis .

Recipe 1.Retrieving All Rows and Columns from a Table

Problem
You have a table and want to see all of the data in it.

Solution
Use the special “*” character and issue a SELECT against the table:

1 select *
2 from emp

Discussion
The character “*” has special meaning in SQL. Using it will return every column for the table specified. Since there is no WHERE clause specified, every row will be returned as well. The alternative would be to list each column individually:

select empno,ename,job,sal,mgr,hiredate,comm,deptno
from emp
In ad hoc queries that you execute interactively, it’s easier to use SELECT *. However, when writing program code it’s better to specify each column individually. The performance will be the same, but by being explicit you will always know what columns you are returning from the query. Likewise, such queries are easier to understand by people other than yourself (who may or may not know all the columns in the tables in the query).

Discovering Islam…

 

 

 

[Akbar Ahmed : The Ibn Khaldun Chair of Islamic Studies and Professor
of International Relations, American University, Washington, D.C.]

==============================================================

The images of Islam prevalent in the world are of brutality, fanaticism, hatred and disorder: Libyans killing policewomen in London, Palestinians hijacking passenger planes, Iranians seizing foreign embassies and Indonesians blowing up the Borobudur temple in Java. The very names of the Muslim leaders of our times—Khomeini, Gaddafi, Arafat—have become symbols of these images. It is V.S.Naipaul’s vision of Islam and Muslims (Among the Believers: An Islamic Journey, 1981): ‘Rage was what I saw…Muslims crazed by their confused faith.’

 

These images stem partly from a lack of understanding of Islam among non-Muslims and partly from the failure by Muslims to explain themselves. The results are predictable: the hatred feeds on hatred. I saw ‘kill a Muslim for Christmas’ written in the London underground stations. Following a nuclear holocaust, American science fiction writer Robert Heinlein has the white survivors enslaved, men castrated and baby girls eaten by Black Muslims, neatly fusing religious and racial prejudices (Farnham’s Freehold, first published in the 1960s). The Muslim leaders, hated and despised, are reduced to Walt Disney villains: ‘Kho Maniac, Wacky Kaddafi, Yucky Arafat’ (‘Garbage pail adults’, MAD, back cover, September 1986). The repugnance is contagious. Even the staid London Economist is not immune and panders to the stereotype: ImamKhomeini was ‘Savonarola’ and Colonel Gaddafi ‘the Devil’s godfather’ on its covers. The colours, red and black, were striking and indicated hell; both men appeared minatory and forbidding.