Page 268 - PYTHON-12

12.15 SQL ALIASES

SQL aliases are used to give an alternate name, i.e., a temporary name, to a database table or a
column in a table. We can rename a table or a column temporarily by giving another name called
alias name which leads to a temporary change (renaming) and does not change the actual name in
the database.
Aliases can be used when

• more than one table is involved in a query.
• functions are used in the query.

• column names are big or not very readable.
• two or more columns are combined together.

Using column alias name, we can give different name(s) to column(s) for display (output) purpose
only. They are created to make column names more readable. SQL aliases can be used both for
tables as well as columns.
• COLUMN ALIASES are used to make column headings in the query result set easier to read.

• TABLE ALIASES are used to shorten a table name by giving an easy alternate name, making it
easier to read or when performing a self-join (i.e., listing the same table more than once in the
FROM clause).
Syntax for table alias:

SELECT <columnname1>, <columnname2>.....

FROM <table_name> AS <alias_name>;

WHERE [<condition>];
Syntax for column alias:

SELECT <column-name> AS <“alias_name”>
FROM <table_name>

WHERE [<condition>];
For example,
Table: Student

Student_name Date-of-birth SELECT Name AS “Student_name”, DOB AS “Date_of_birth”
Raj Kumar 17-Nov-2000
Deep Singh 22-Aug-1996 FROM student;
Computer Science with Python–XII 12.38 Diksha Sharma 17-Dec-1999
02-Feb-2000
Ankit Sharma
Alias name for fields, Name and DOB
Radhika Gupta
03-Dec-1999
21-April-1998
Payal Goel
Gurpreet Kaur
04-Jan-2000
05-May-1997
Akshay Dureja
08-Oct-1999
Shreya Anand
25-Dec-2000
Prateek Mittal
10 rows in a set (0.02 sec)