ALIASES - (Oracle Misc)

Aliases in Oracle are used to provide an alternative name for a table or a column in a table. This can be useful in cases where the original names are too long or complex. Aliases are commonly used when writing complex SQL queries that involve multiple tables.

Syntax

The syntax for creating a table alias in Oracle is as follows:

SELECT column_name1 AS alias_name1, column_name2 AS alias_name2 
FROM table_name;

The AS keyword is optional and can be omitted. The alias name is used in place of the column name in the SELECT clause.

Example

Here is an example of using table aliases in a SQL query:

SELECT e.first_name, e.last_name, d.department_name AS dept
FROM employees e
JOIN departments d
ON e.department_id = d.department_id;

In the above example, we are selecting the first name and last name of employees from the employees table. We are also selecting the department name from the departments table and giving it an alias called dept. We are joining the two tables on the department_id column.

Output

The output of the query will be a table with three columns - first name, last name, and department name, with the latter being displayed as dept.

Explanation

In the above example, we have used table aliases to provide a shorter and more convenient name for the departments.department_name column. This makes the query more readable and easier to understand.

Use

Aliases in Oracle are commonly used in complex SQL queries that involve multiple tables or columns. They can help to simplify the query and make it easier to read and understand.

Important Points

• Aliases provide an alternative name for a table or a column in a table.
• Aliases are commonly used in complex SQL queries that involve multiple tables or columns.
• The AS keyword is optional and can be omitted when defining an alias.

Summary

In summary, aliases in Oracle are useful for providing alternative names for tables or columns in a table. They are commonly used in complex SQL queries that involve multiple tables or columns and can help to simplify the query and make it more readable.