Hi,

How can we develop transaction based system like event management system in SharePoint 2013 online( Office 365 E3 version)and manage Transactions (like rollback, commit operation), data integrity, concurrent users update, Primary And foreign keys, Cascading deletes, Large data, Report from multi list. 

Any approach, information, code about this would be greatly appreciated. Thanks!

Hi, i don't think there is a straight forward answer for this question, without first understanding your development experience.

You may want to starts with understanding SharePoint Online / SharePoint Add-Ins concept. Your might want to explore the following URL,

https://msdn.microsoft.com/en-us/library/office/fp179924.aspx

In theory you are able to build business applications on SharePoint, with the usual CRUD capabilities, and even workflow, however, do bear in mind that you will not have the rollback / commit concept like you used to have dealing with SQL.