Understanding the Use of Alias in SQL

The SQL alias syntax is a handy tool that can be used to give a table, or a column in a table, a temporary name. It's used to make column names more readable and to condense complex queries. According to the question, the correct syntax for using an alias in SQL is SELECT EmployeeID AS ID FROM Employees.

In this statement, EmployeeID is the actual name of the column in the 'Employees' table from our database, and ID is the alias we are assigning to it. The AS keyword is used to create the alias. So, instead of displaying 'EmployeeID' as the column name, our output would display it as 'ID'. This might seem trivial with such a simple query, but when dealing with complex, nested queries, an alias can save time and reduce errors.

Here's another practical example of using alias in SQL. Assume you have a Sales table with price and quantity columns, and you want to compute the total cost for each row. Instead of typing price * quantity each time you want it, you can use an alias:

SELECT price * quantity AS 'Total Cost' FROM Sales

Now, you can simply refer to 'Total Cost' in other parts of your query.

In terms of best practices, it's usually a good idea to use aliasing when dealing with joins and subqueries, or when the column names are complex or not self-explanatory. Remember though, the actual database schema is not changed. Aliases only exist for the duration of the query.

In conclusion, using an alias in SQL can streamline your SQL queries and make your data results easier to read and understand. Remember that the alias disappears once the SQL query is executed. Therefore, aliases should be used carefully, especially when query results are used for further data processing activities.