I've set up a portal to capture holiday leave dates as part of an employee's record. The three most important fields are: LeaveStart, LeaveEnd and Duration (which is calculated end - start). I then applied a calculated validation to the two date fields to ensure that they are within the current year and that end > start. The calculations function well but validation only occurs when the user clicks out of the portal, by which time they could have entered several rows of screwy date ranges and calculated durations.
How can I get the validation to occur as the user steps out of each field? This is how it works for other "built-in" validation such as four-digit years and correct number of days for a month or months in a year e.g. 88/88/2016 would be immediately flagged up as an error.