TO_YMINTERVAL
                                                            Purpose
This function converts a string value into an interval (INTERVAL YEAR TO MONTH).
Syntax
to_yminterval::=
                                                                        
                                                                    
Usage Notes
- The string always has format 
[+|-]YY-MM. Valid values are0to999999999for years(YY)and0to11for months(MM). - For additional information, refer to TO_DSINTERVAL, NUMTODSINTERVAL, and NUMTOYMINTERVAL.
 
Example
SELECT TO_YMINTERVAL('3-11') TO_YMINTERVAL;