Android Roster/Calendar APP

HI, What I am looking for is a app that staff can load their rosters into. We have a 3month Roster in advance and at the moment we have to write down week by week the the start times its a huge pain trying to add them to a calendar and we have a number of employees that keep making mistakes not turning up or late. We have a workplace where we change and do different jobs on a daily cycle. All start times are coded on a spread sheet withy the date above and the following code across from their name. PM1500 = Production Mixer 1500 HRS WH0800 = Warehousing 0800HRS etc etc etc So what I am looking for is an app that I can easily input the start and finish times into a calendar like Google calendar via a drop down box. The codes need to be kept in a DB of some type I guess that can be edited so more codes can be added for different workers some may have a number of jobs some just a few. So pick the day on the calendar dropdown box appears pick the code it inserts the start time etc into that day on the calendar save exit or next to do the next day. I would love to get to a situation where I can push this out or they can download from a webserver but for the short term this should solve many issues and they can enter the codes etc themselves. Needs to look clean like google calendar not overly colourful. The right coder will get further work on this project.