In PostgreSQL, the abs() function returns the absolute value of its argument.

The absolute value means how far the number is away from zero. Therefore, the absolute value of 7 is 7, and the absolute value of -7 is also 7.

Therefore, any negative values passed to abs() are returned as positive values. Positive values and zero are returned unchanged.

Syntax

The syntax is quite simple:

abs(x)

Where x is the argument you provide in order to get the absolute value.

Example

Here’s an example to demonstrate its usage.

SELECT abs(-58);

Result:

58

In this case I provided a negative value (-58) and it returned its positive equivalent (58).

Positive Values

If I pass a positive value, it is returned unchanged.

SELECT abs(58);

Result:

58

Zero

Zero is also returned unchanged.

SELECT abs(0);

Result:

0

Expressions

The abs() function can return the absolute value of expressions such as the following.

SELECT abs(-20 * 5);

Result:

100

Just to be clear, here it is again compared to the actual output of the expression.

SELECT 
  (-20 * 5) AS "Result of Expression",
  abs(-20 * 5) AS "Result of abs(Expression)";

Result:

Result of Expression | Result of abs(Expression)
----------------------+---------------------------
-100 | 100