Search content through files

Hi to all,
Basic Concept : 
1. User will upload files into system. {say into Database or storing in some location (C:/temp/.....).}
2. Suppose user wants to search file/s which contains particular keywords - suppose user wants to retrieve files which contains word : Finance Management. System should return all the files which contains that word.
I know how to upload file and retrieve file of particular name.
Problem : Only need idea of functionality in which key word will be searched through the several files and search result will return names of the files which contain that word.
Please help me.
Thank you


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