Column Alias in ORACLE

• Column alias renames a column heading in a query.
• Its an alternate name for an exiting oracle object.
• The column alias is specified in the SELECT list by declaring the alias after the column name by using the space separator.
• Alias heading appears in UPPER casing by default.
• The alias should be declared in double quotes (“ “).
• Alias is declared after the column with minimum of one space.
• The AS keyword can be used between the column name and alias.
• An alias effectively renames the SELECT list item for duration of the query only.
• An alias cannot be used, any where in the SELECT list for operational purpose.

Note  : Never consider Alias as a column

Example :=

         1)    Select 20 + 10 Mysum from dual;

         2)   Select ename, sal salary, comm commission from emp;

         3)   Select sal “Basic Salary” from emp;

         4)   Select ename, empno, sal AS Salary from emp;

         5)   Select empno AS Numbers,  

Ename AS Name,

Job AS Designation,

Sal AS  Salary,

Hiredate AS JoinDate

From emp;

- - Either use Numbers or Use as “Number” as a alias, never use Number as a alias.