Opposite number

Very simple, given an integer or a floating-point number, find its opposite.

Examples:

1: -1
14: -14
-34: 34

You will be given a table: opposite, with a column: number. Return a table with a column: res.

 

Solution:

SELECT
  number * -1 AS res  
FROM 
  opposite

 

 

Below is a method to solve uselessly and difficultly using CASE and SIGN.

The 'SIGN' function tells whether the number is negative or positive with '1' and '-1'.

SELECT
  (CASE WHEN SIGN(number)=1 THEN number*-1
  WHEN SIGN(number)=-1 THEN number*-1 END)
  AS res
FROM 
  opposite