Organize SQL Database into an Excel Spreadsheet

I work for a homeless shelter that has a peer based addiction recovery program imbedded within it. We are implementing a new data management system. Our old system is piecemealed together and is 20 years old. We need to export 20 years of client data---nights stayed in a homeless shelter/recovery program--into an Excel spreadsheet. Unique individuals have various entry and exit dates and length of time they have stayed with us. It seems relativity easy, but we don't know how to do it.