If you have developed business applications with Java, you have most likely used JDBC directly or indirectly(through an object-relational mapping framework) to connect and use relational databases. A relational database is a system for storing information in a tabular form; that is, in tables. There are many vendors offering free and commercial relational database management systems (RDBMS). Two of the most popular open source RDBMS are PostgreSQL and MySQL, while Oracle Database and Microsoft SQL Server are well-known options among the commercial ones. These systems understand the Structured Query Language (SQL), a declarative language used to perform tasks such as adding or deleting rows in a table.
When using a declarative language, you specify what you want the program to do. In contrast, when using an imperative language, such as the Java programming...
