It, network/system/database/software development

I am familiar with many aspects of this industry. I graduated from a computer science university for two years. One day, a college student sent a message asking me, "would you use Delphi as a system? "I answered" no ".
Looking back, I have been working in the IT industry for several years. I still like to do something about small systems at school. after graduation, I also worked on software for a period of time. However, most of the time I was engaged in networking, and I had a lot of contact with hardware. For Network Programming and software development, database development has been less active and has no enthusiasm for doing so. In this age where the software industry is more popular than the network industry, how can I do without any knowledge of software development?
At least master our networkProgramming Language(Software development | Database Development) + integrated development environment + development tools !!