Depends on what kind of reports you want to create and the budget you have got,
I have had some good experience with SSRS.
They have standard export to PDF, Excel, CSV, ...
Also available for mobile and such.
It can get you started real quick. However getting the full SSRS experience might take some what longer. (SSAS, SSIS, Cubes, Wharehouses, ...)
In the webapplication you could use an Iframe that takes the URL of the report you have created. It also supports parameters in the URL so you could build your URL depending on the textboxes, dropdowns, or whatever.
A good explanation what it is all about:
here
There are some good third party tools out there like
infragistics (pretty expensive). I have not used it for web but I did use it for WPF and their datagrid standard supports grouping, filtering (excel like), summaries on the grouping, and so on.
Hope this helps.
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