While using the dateadd() function to add the given number to an existing year, it adds the days instead of years if we use the command in the following manner:
If the date is entered in “mm-dd-yy” format,
dateadd("yy",5,"07-01-99"), the output will be “07-06-99”.
If we use:
dateadd("yyyy",5,"07-01-99"), then the output will be “07-01-04”.
I would like to know why it is adding the days instead of year if we use the first syntax [dateadd (“yy”,5,”07-01-99″)]?
The main reason this doesn’t work the way you expect it to is that “yy” is not an acceptable parameter.
According to Microsoft’s documentation, you can add days to a date with either a single y, d, or w. It looks like the function is assuming that yy = y and is adding days to the date. If you want to add years, use the yyyy parameter you used in the second sample.