The SIGN function returns the sign of a given number. It returns 1 for a positive value, -1 for a negative value, and 0 for zero.
SIGN(number_operand)
--it returns the sign of the argument
SELECT SIGN(12.3), SIGN(-12.3), SIGN(0);
sign(12.3) sign(-12.3) sign(0)
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1 -1 0