Standard Query Language (SQL) is a computer language for communicating with databases. As a part-time SQL developer, you help design databases using SQL code. Your duties may also include creating applications that help users interface with databases. After you develop a database or related tools, your responsibilities shift to testing your code to ensure quality and usability. As a part-time developer, you may design and test one data application or one facet of a larger database development project. Since you work part-time, you need to document your work and adhere to the development methodologies that your team is using.