I need advice for which database system to use

I have to create a database from scratch for the first time and I am not sure which system I should try. I will have specific IP addresses, IP ranges, domain names, host names which will be the key for a given customer. I want my database to be filterable by the customer's key. Each key will have a variety of different forms of data associated with it. For example, a key may have a list of open ports, any identified services, etc. Sometimes a key will be a website, and the data associated with it may be cookie names, URLs, and parameters. If I later find out that a customer's parameter is vulnerable, I want to be able to search through all of the customer's for that vulnerability. What database system should I try using? What would be the most flexible and efficient? I don't want to try a database that isn't for my scheme.