ORACLE Part 5

Defining Columns Alias

A Column Alias is basically nickname of the column heading, It is useful in Calculations.

You can use Column Alias by following ways.
1. Immediately After the Column Name
2. Also use it in Double quotations
3. Never used keywords in Aliases but we can used in double quotations

SELECT ENAME "SELECT" FROM EMP;

--CONCATENATION

/* CONCATENATES COLUMNS OR CHARACTER STRING TO OTHER COLUMNS, REPRESENTED BY TWO PIPE SIGNS (||) */

SELECT ENAME || 'WORK AS' || JOB || 'SINCE' || HIREDATE || 'IN DEPARTMENT' || DEPTNNO FROM EMP;

FOR AVOIDING DUPLICATION IN RETRIEVING DATA
-- DISTINCT KEYWORD USED
-- DISTINCT KEYWORD ALWAYS APPEAR AFTER THE SELECT STATEMENT
SELECT DISTINCT DEPTNO FROM EMP;