Hi Sanjay,
What you are looking to do is prevent a record being saved when the date entered in your second date field in a record is before the first date field in a record correct? If so that is actually something that can be done using
Custom Data Rules on the table. Custom data rules can be set up on a table to prevent records from being saved, and to display a custom error message, when their conditions are not met. For example if the date in one field is on or before the date in another it could be set up to display a message like "All follow up appointments have to fall after the initial appointment date". This allows you to prevent a record from being saved and also give guidance to the end user so they can go back and fix it. I linked above the help doc for custom data rules and how you can get started but certainly let me know if you have follow up questions and I hope this helps.
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Evan Martinez
Community Marketing Manager
Quick Base
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