Auto Generated Field in Appian Interface/Form

Question

Hi, 
 I have 2 question for the community. 
 
 (1) Is it possible to create a field in form (say id) which can auto populates its value in sequence ? 
 I have a form and i want to generate one ID field which user can see only on creating a new record and it should auto populate like 1,2,3,4 etc each time when someone creates a new record. 
 Is it possible to do in Appian forms? 
 
 (2) Can i create dynamic forms in Appian ? I have one dropdown column. Based on the value of the Dropdown field can i create other box ? 
 For ex- If in one dropdown i have values 1,2 if user selects 1 then in next dropdown only A,B values should come and if user selects 2 then C,D value should appear as option in next dropdown. 
 Is it possible to do in Appian forms ?

Paurush Saxena · Accepted Answer

For #1, the better option may be to use the database sequence/auto_increment once the record is successfully submitted by the user. And, display the generated ID as a confirmation of submission. If you query ahead, then it may lead to concurrency issues.

Josh · Answer

1. If your records are entity backed, you could use a query to find the last sequence number and increment by one. You'll need to consider the case of multiple users initiating a new record at the same time. 
 
2. This is possible, here is an example of dynamic component behavior: docs.appian.com/.../recipe_add_multiple_text_components_dynamically.html

aloks0189 · Answer

Hi prais1852 , as per my understanding, yes, you can query the DB on load of an Interface and then increase the Value by 1, but when it's the case of Concurrency, i think it's gonna to push you into trouble. 
 
I do not understand, why do you want to show the Auto Generated id (i.e. 1,2,3,4 etc..) to the End User, because i don't think, this is going to help the End user from any perspective, don't know why exactly you want to show this to end user. 
 
If it is about Auto generated Reference Number to show to End User, then i suggest Create a Rule to generate one Auto generated Reference number, which will contain some Characters appended with Date, Month, Year, Hour, Minute, Second, Millisecond , which will give you a unique Auto generated Value for each user (While working in Concurrency as well) and the Same you can persist into DB against that user into an another column, let's say named as uniqueRefNo 
 
for example: 
concat("REF-",text(today(), "ddMMyyyy"),hour(now()),minute(now()), second(now()), milli(now()))