Returns the sign of an input value. This function is an additional function of MaxCompute V2.0.
Syntax
double sign(<number>)Parameters
number: required. A value of the DOUBLE, BIGINT, INT, SMALLINT, TINYINT, FLOAT, DECIMAL, or STRING type.
Return value
A value of the DOUBLE type is returned. The return value varies based on the following rules:
If the value of number is a positive value, 1.0 is returned.
If the value of number is a negative value, -1.0 is returned.
If the value of number is 0, 0.0 is returned.
If the value of number is null, null is returned.
Sample data
This section provides sample source data and examples for you to understand how to use the functions. In this topic, a table named mf_math_fun_t is created and data is inserted into the table. Sample statements:
create table if not exists mf_math_fun_t(
int_data int,
bigint_data bigint,
double_data double,
decimal_data decimal,
float_data float,
string_data string
);
insert into mf_math_fun_t values
(null, -10, 0.525, 0.525BD, cast(0.525 as float), '10'),
(-20, null, -0.1, -0.1BD, cast(-0.1 as float), '-10'),
(0, -1, null, 20.45BD, cast(-1 as float), '30'),
(-40, 4, 0.89, null, cast(0.89 as float), '-30'),
(5, -50, -1, -1BD, null, '50'),
(-60, 6, 1.5, 1.5BD, cast(1.5 as float), '-50'),
(-1, -70, -7.5, -7.5BD, cast(-7.5 as float),null ),
(-80, 1, -10.2, -10.2BD, cast(-10.2 as float), '-1' ),
(9, -90, 2.58, 2.58BD, cast(2.58 as float), '0'),
(-100, 10, -5.8, -5.8BD, cast(-5.8 as float), '-90');Query data from the mf_math_fun_t table. Sample statement:
select * from mf_math_fun_t;
-- The following result is returned:
+------------+-------------+-------------+--------------+------------+-------------+
| int_data | bigint_data | double_data | decimal_data | float_data | string_data |
+------------+-------------+-------------+--------------+------------+-------------+
| NULL | -10 | 0.525 | 0.525 | 0.525 | 10 |
| -20 | NULL | -0.1 | -0.1 | -0.1 | -10 |
| 0 | -1 | NULL | 20.45 | -1.0 | 30 |
| -40 | 4 | 0.89 | NULL | 0.89 | -30 |
| 5 | -50 | -1.0 | -1 | NULL | 50 |
| -60 | 6 | 1.5 | 1.5 | 1.5 | -50 |
| -1 | -70 | -7.5 | -7.5 | -7.5 | NULL |
| -80 | 1 | -10.2 | -10.2 | -10.2 | -1 |
| 9 | -90 | 2.58 | 2.58 | 2.58 | 0 |
| -100 | 10 | -5.8 | -5.8 | -5.8 | -90 |
+------------+-------------+-------------+--------------+------------+-------------+Example: static data
-- The return value is -1.0.
select sign(-2.5);
-- The return value is 1.0.
select sign(2.5);
-- The return value is 0.0.
select sign(0);
-- The return value is null.
select sign(null);Example: table data
Obtain the signs of values in all columns based on the Sample data. Sample statement:
-- Enable the MaxCompute V2.0 data type edition. Commit this command along with SQL statements.
set odps.sql.type.system.odps2=true;
select sign(int_data) as int_new, sign(bigint_data) as bigint_new, sign(double_data) as double_new, sign(decimal_data) as decimal_new, sign(float_data) as float_new, sign(string_data) as string_new from mf_math_fun_t;The following result is returned:
+------------+------------+------------+-------------+------------+------------+
| int_new | bigint_new | double_new | decimal_new | float_new | string_new |
+------------+------------+------------+-------------+------------+------------+
| NULL | -1.0 | 1.0 | 1 | 1.0 | 1.0 |
| -1.0 | NULL | -1.0 | -1 | -1.0 | -1.0 |
| 0.0 | -1.0 | NULL | 1 | -1.0 | 1.0 |
| -1.0 | 1.0 | 1.0 | NULL | 1.0 | -1.0 |
| 1.0 | -1.0 | -1.0 | -1 | NULL | 1.0 |
| -1.0 | 1.0 | 1.0 | 1 | 1.0 | -1.0 |
| -1.0 | -1.0 | -1.0 | -1 | -1.0 | NULL |
| -1.0 | 1.0 | -1.0 | -1 | -1.0 | -1.0 |
| 1.0 | -1.0 | 1.0 | 1 | 1.0 | 0.0 |
| -1.0 | 1.0 | -1.0 | -1 | -1.0 | -1.0 |
+------------+------------+------------+-------------+------------+------------+Related functions
SIGN is a mathematical function. For more information about functions related to data computing and conversion, see Mathematical functions.