Hello friend, before continuing, thank you for your teachings through this medium, it is always great to be able to find people like you and this channel, who help others understand, discover and solve similar situations in their own cases.

From now on, you have a loyal follower of your YouTube channel.

Well friend, I am trying to do something very similar to what you propose in this video, (Validating Field Values with JetFormBuilder Server side Callback for Single Field and Query Builder) in fact I consider it to be much simpler, even so, it ends up being quite complex for me.

I am trying to have an alphanumeric text field in my form created with jet form builder, which must validate that there are no two equal values, I will use this field for the unique user registration on my site and this alphanumeric field corresponds to the person's identity document number, which must be unique in the world, at least within my country.

So, I have this alphanumeric field, which I hope will be validated as a unique value that cannot be repeated, that is, if I register and in that field, I will call it DNI (ID of each person) and I use the value A12345678 and then you come and want to register you have to put your DNI number (ID), but I want to avoid someone trying to use another person's DNI, and that is why I require this field, so that another person (you following this hypothetical example) cannot use the DNI: A12345678, you can use B12345678, (but in no way A12345678), now, when a third user comes and tries to use your DNI number B12345678 or mine A12345678, then he cannot use either of those two values ​​that are already registered in the Jet Engine CCT database table.

I hope I can make myself understood and I would like to know if you can help me with my problem.

P.S., I speak Spanish, not English, so I appreciate, thank and value your videos very much because you explain without rushing.

See try: https://themandiva.org/