Hi,

The company must have your cv considering that you have this interview and they know that you have a civil engineering background. So firstly they wont judge you like they would a CS or IT candidate. As for the interview, if you know the basics and seem good enough to be trained, they should select you. Check the job profile, see what the job entails, brush such topics that may be required and are a necessity say for example many software jobs ask for knowledge of OOPS, or data base. If you dont know, ensure you make the point that you can learn and come up to expectations. All the best!