Dynamic lookup AEM UI Component

Hi 

You question is actually divided into two parts:

1. AEM-RDBMS intigration or getting value from RDBMS into AEM.

2. Autocomplete feature

For part 1, please refer to these helx articles 

Link:- https://helpx.adobe.com/experience-manager/using/querying-persisting-cq-data-mysql.html

// here we are Querying and Persisting Adobe AEM data into MySQL and can do Vice-verse

Link:-  https://helpx.adobe.com/experience-manager/using/creating-cq-web-application-uses.html

//Creating an Adobe CQ web application that uses MySQL

For Part 2:-

What you can do is, fetch the data from Mysql and save it at JCR level. Now, we can create a Custom Search component (Many Jquery plugins are available for search and Auto complete) which will consult only data from particular Ajex call. This data can be cached in dispatcher so next time when we query the data we can use cached data. Autocomplete thing can be achieved easily by Jquery/

Dispatcher :- https://docs.adobe.com/docs/en/dispatcher.html

Dispatcher :- https://docs.adobe.com/content/docs/en/dispatcher/disp-config.html

AEM Jquery Component:- https://helpx.adobe.com/experience-manager/using/custom-carousel-components.html

Jquery Demo Autocomplete :- https://jqueryui.com/autocomplete/

AutoComplete Jquery Via AJEX:- https://www.sitepoint.com/10-ajaxjquery-autocomplete-tutorial-examples/

HTTP Cache can also be an option for caching :-https://adobe-consulting-services.github.io/acs-aem-commons/features/http-cache.html

I hope this could be of some use to you.

Thanks and Regards

Kautuk Sahni