departmentname departmentid sql table_name truncate codd aliasing obfuscation query schemas bindings readability relational queries keyword alias ansi keywords iec xml rename delete omit programmer modules aliases routines permissible assigning null
when creating a query what is the purpose of including a column alias
Alias ( SQL ) - wikipedia Alias ( SQL ) Jump to : navigation , search This article needs additional citations for verification . Please help improve this article by adding citations to reliable sources . Unsourced material may be challenged and removed . ( October 2013 ) ( Learn how and when to remove this template message ) An alias is a feature of SQL that is supported by most , if not all , relational database management systems ( RDBMSs ) . Aliases provide database administrators , as well as other database users , with the ability to reduce the amount of code required for a query , and to make queries simpler to understand . In addition , aliasing can be used as an obfuscation technique to protect the real names of database fields . In SQL , you can alias tables and columns . A table alias is also called a correlation name . A programmer can use an alias to temporarily assign another name to a table or column for the duration of a SELECT query . Assigning an alias does not actually rename the column or table . This is often useful when either tables or their columns have very long or complex names . An alias name could be anything , but usually it is kept short . For example , it might be common to use a table alias such as `` pi '' for a table named `` price_information '' . The general syntax of an alias is SELECT * FROM table_name ( AS ) alias_name . Note that the AS keyword is completely optional and is usually kept for readability purposes . Here is some sample data that the queries below will be referencing : Department Table DepartmentID DepartmentName 31 Sales 33 Engineering 34 Clerical 35 Marketing Using a table alias : SELECT D. DepartmentName FROM Department AS D We can also write the same query like this ( Note that the AS clause is omitted this time ) : SELECT D. DepartmentName FROM Department D A column alias is similar : SELECT d. DepartmentId AS Id , d. DepartmentName AS Name FROM Department d In the returned result sets , the data shown above would be returned , with the only exception being `` DepartmentID '' would show up as `` Id '' , and `` DepartmentName '' would show up as `` Name '' . Also , if only one table is being selected and the query is not using table joins , it is permissible to omit the table name or table alias from the column name in the SELECT statement . Example as follows : SELECT DepartmentId AS Id , DepartmentName AS Name FROM Department d <Th_colspan="2"> SQL Versions SQL - 86 SQL - 89 SQL - 92 SQL : 1999 SQL : 2003 SQL : 2006 SQL : 2008 SQL : 2011 SQL : 2016 Keywords As Case Create Delete From Having Insert Join Merge Null Order by Prepare Select Truncate Union Update Where With Related Edgar Codd Relational database ISO / IEC SQL parts Framework Foundation Call - Level Interface Persistent Stored Modules Management of External Data Object Language Bindings Information and Definition Schemas SQL Routines and Types for the Java Programming Language XML - Related Specifications References ( edit ) Jump up ^ ANSI Standard SQL - Foundation Document - Date : 2010 - 10 - 14 Retrieved from `` https://en.wikipedia.org/w/index.php?title=Alias_(SQL)&oldid=781026809 '' Categories : SQL Hidden categories : Articles needing additional references from October 2013 All articles needing additional references Talk About Wikipedia Українська Edit links This page was last edited on 18 May 2017 , at 17 : 06 . About Wikipedia