SQL Aliases

Aliases are giving a temporary name to a column in a table or table itself. But it exists only while the query is executing.

Consider the below EMPLOYEE table

EMPLOYEE_ID	FIRST_NAME	LAST_NAME	EMAIL	SALARY
100	Steven	King	SKING	24000
101	Neena	Kochhar	NKOCHHAR	17000
102	Lex	De Haan	LDEHAAN	17000
103	Alexander	Hunold	AHUNOLD	9000
104	Bruce	Ernst	BERNST	6000
105	David	Austin	DAUSTIN	4800
106	Valli	Pataballa	VPATABAL	4800
107	Diana	Lorentz	DLORENTZ	4200
108	Nancy	Greenberg	NGREENBE	12008
109	Daniel	Faviet	DFAVIET	9000

In the below example, the select clause uses an arithmetic expression like salary/2 as an attribute,

Select first_name, salary/2

From employees

Where salary = 17000;

It displays the result-set as follows,

FIRST_NAME	SALARY/2
Neena	8500
Lex	8500

Here replace the salary/2 attribute name to Half_Salary by using aliases.

Example,

Select first_name, salary/2 as Half_Salary

From employees

Where salary = 17000;

FIRST_NAME	HALF_SALARY
Neena	8500
Lex	8500

Here notice the change in column name from salary/2 to Half_salary after using aliases. We can also give a temporary name to the table, which helps to reduce the coding error.

SQL Tutorial

Introduction Of SQL

Data Access and Retrieving Data from Table

Summarizing and Grouping Data

Using Joins

Creating Altering and Dropping Tables

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Miscellaneous SQL Concepts

SQL Aliases

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