Sir can you please guide me that which computer courses are mandatory to learn for getting a software job in campus placements after b.tech

To get a entry in software field you need to understand programming logic, data structure, database knowledge and if you have command in programming skill it's an added advantage. Go for c,c++ or java which is very common. you can have other languages like PHP or unix level programing like python o

Most of the people ask to write a logic And they will not specify any particular programming language. I suggest u to learn c,java.