Aliases in SQL

In this post, we’ll go over aliases in SQL Server. The following are some key points about Aliases.

In SQL Server, aliases can be used to create a temporary name for columns or tables.
Column aliases are used to make column headings easier to read in your result set.
Table aliases are used to shorten your SQL for easier reading or when performing joins.
An alias exists only for the duration of the query.
The AS keyword is used to create an alias, but it is not required in all SQL Products.
We frequently get No Column Name as the output column name when performing arithmetic expressions, concatenating columns, or calling system or built-in functions in the select statement. We can use Alias to provide a meaningful name for it.

Examples:
SELECT first_name + ‘ ‘ + last_name
FROM tbStudents
ORDER BY first_name;

This returns the output by combining the first_name and last_name of the student from the table. However, the column name will be No Column Name. To avoid this, we can use the alias as shown below.

SELECT first_name + ‘ ‘ + last_name AS FullName
FROM tbStudents
ORDER BY first_name;

The following is an example of how to shorten table names by assigning alias names to them. It means that the alias will be used to represent/refer to the actual table.

SELECT * FROM tbStudentsInformation AS S
JOIN tbStudentsPayments AS P ON S.iStudentID = P.iStudentID;

The following is an example to shorten the column names in the output.

SELECT
first_name + last_name AS StudentName,
MIN(PaymentDate) FirstPaidDate,
MAX(PaymentDate) RecentPaidDate
FROM tbStudentsInformation AS S
JOIN tbStudentsPayments AS P ON S.iStudentID = P.iStudentID
GROUP BY first_name + last_name;