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Overview

The SIGN() function returns a sign of an argument. The returned values are -1 if the argument is less than zero, 1 if the argument is greater than zero, 0 if the argument is equal to zero.

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Syntax

The syntax for the SIGN() function is as follows: 
SIGN(x)
The SIGN() function requires one argument:
  • x: an expression that evaluates to a number.

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Examples

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Case #1: Sign of a number

The following example demonstrates how the SIGN() function can be used to obtain the sign of a number: 
SELECT
    SIGN(0.1) AS "SIGN(0.1)",
    SIGN(999) AS "SIGN(999)",
    SIGN(0) AS "SIGN(0)",
    SIGN(-0) AS "SIGN(-0)";
The query will return the signs of the passed arguments: 
 SIGN(0.1) | SIGN(999) | SIGN(0) | SIGN(-0)
-----------+-----------+---------+----------
         1 |         1 |       0 |        0
Note: -0 is accepted as an argument and is equal to zero

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Case #2: SIGN() function with an expression

The following example demonstrates how the SIGN() function can be used with an expression: 
SELECT SIGN(100 - 200);
will return the sign of the expression evaluation: 
 sign
------
   -1
------

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Case #3: Using the SIGN() function with a table

The following example demonstrates how the SIGN() function can be used with a table to obtain the absolute values of all numbers in a specific column:
  1. Create a table signTable containing an value column with some positive, negative and equal to zero values:
CREATE TABLE signTable(value float);

INSERT INTO signTable(value)
VALUES 
(1000),
(-200),
(0),
(0.22),
(-12.3),
(-0.0);
  1. Use the following query to find the sign of all inserted values:
SELECT value, SIGN(value) AS sign
FROM signTable;
  1. The result will be as follows::
 value | sign
-------+------
  1000 |    1
  -200 |   -1
     0 |    0
  0.22 |    1
 -12.3 |   -1
    -0 |    0