File validation while uploading in a table

Hi Experts,

For an Excel file uploading using File uploading UI element i need to validate what type of file is uploading?

Except Excel other file should not upload any say error message?

And i need to validate each filed validation in excel while uploading in a table if not we need to pass error messages into one internal table?

And records should be saved after uploading using excel in a table as well as in database?

Can any one help me on this.

Thanks,

Venkatesh