SIGNBIT

Description

判断给定浮点数的符号位是否为负。

Syntax

SIGNBIT(<a>)

Parameters

Parameter	Description
<a>	要检查的浮点数参数

Return Value

如果 <a> 的符号位为负（即 <a> 是负数），返回 true，否则返回 false。 特别的，对于浮点数的正负零，也可以区分。

Examples

select signbit(-1.0);

+-----------------------------+
| signbit(cast(-1 as DOUBLE)) |
+-----------------------------+
| true                        |
+-----------------------------+

select signbit(0.0);

+----------------------------+
| signbit(cast(0 as DOUBLE)) |
+----------------------------+
| false                      |
+----------------------------+

select signbit(1.0);

+----------------------------+
| signbit(cast(1 as DOUBLE)) |
+----------------------------+
| false                      |
+----------------------------+

select signbit(cast('+0.0' as double)) , signbit(cast('-0.0' as double));

+---------------------------------+---------------------------------+
| signbit(cast('+0.0' as double)) | signbit(cast('-0.0' as double)) |
+---------------------------------+---------------------------------+
|                               0 |                               1 |
+---------------------------------+---------------------------------+