SQL query result in Random Order

Usually a SQL result is desired either in ascending or descending order based on a column.

But what if you want the result in a random order based on your choice.

Here is an example,

Problem - Display job id and department id of departments 10, 50, 20 in that order. 

Solution - At first, it seems to be a simple sql query but I have to think more on how to get the order 10, 50 and 20, its neither ascending nor descending.

Concept - Introduce a new dummy column in the select list and order by it. Select only two columns from the final result. Below is the query.

select job_id, department_id from (

select job_id, department_id, 1 from employees

where department_id = 10

union

select job_id, department_id, 2 from employees

where department_id = 50

uni

on

select job_id, department_id, 3 from employees

where department_id = 20

order by 3

);

I first did the union of individual results. This is required as I have to introduce a new column in each select query and give it a specific value so that I can order it later. Then, apply ascending order on column number 3 ( dummy column ) of the Union result.

Now, I have the result in required order but with one extra column. To remove it, I do a final select of only job id and department id from the union result.

Hope this was informative!

Thank you.