SQL函数：求select sign(?

Question

SQL函数：求select sign(

Answer 1

Oracle/PLSQL: Sign Function
在 Oracle/PLSQL, sign 函数返回一个值来说明数字的符号，语法如下
sign( number )

If number < 0, then sign returns -1.
If number = 0, then sign returns 0.
If number > 0, then sign returns 1.

For example:
sign(-23) would return -1
sign(-0.001) would return -1
sign(0) would return 0
sign(0.001) would return 1
sign(23) would return 1
sign(23.601) would return 1

Answer 2

sign 取得是数据的 符号，当数据为0的时候 返回结果为0。
如：select sign(1-2) from dual; 结果 -1
select sign (-2) from dual; 结果 -1
select sign(-0) from dual; 结果 0