sign function

The sign function returns the sign of the specified expression, that is, zero if the argument is zero, 1 if the argument is greater than zero, and -1 if the argument is less than zero.

Syntax:

double sign(n)

Semantics:

• n: The argument n is an expression that resolves to a number.
• return type: double.
  • Returns 1.0 if n resolves to a positive number.
  • Returns -1.0 if n resolves to a negative number.
  • Returns 0.0 if n resolves to zero.
  • Returns a NULL value in the following cases:
    • n resolves to a NULL value
    • n does not resolve to a number
  • Returns NaN if n resolves to NaN.

Example 12-91 sign function

SELECT sign(n) FROM PHtable

Value of n	Output
1.89	1.0
-1.89	-1.0
0	0.0
sin(3*pi()/2)	-1.0