The NUMTOYMNTERVAL function converts a number to a YMINTERVAL literal.
Any NUMBER value or an expression that can be implicitly converted to a NUMBER value.
A text value that specifies the unit of number and must resolve to one of the following string values: YEAR or MONTH.
interval_unit is case insensitive. Leading and trailing values within the parentheses are ignored. By default, the precision of the return is 9.