What important theoretical subject you have to learn to crack any Software company

These are main theoretical subject you have to focus

• Operating system
• DBMS
• My SQL languages
• Networking
• Data structure
• System Analysis and design

For understanding the concepts of computer 

and crack any placement regarding software company you have to go through these main subjects. 

Here are the some best book to learn these subjects:-

• Operating system by Silberschatz galvin
• DBMS by Abraham Silberschatz
• Networking by Behrouz A. Forouzan, jim kurose. 
• Data structure by Narasimha karumanchi
• System analysis and design by Alan dennis.