Java is a programming language designed to run on any device that can run the JVM (Java Virtual Machine). It is a general-purpose programming language in that the types of problems that Java solve are not constrained to any specific domain. SQL is a database query language designed to query information from relational databases. It is not a general-purpose language like Java but has been ported to many other technologies outside relational database management systems since its inception.
It is important to note that SQL is not technically a programming language but a query language (SQL = Structured Query Langauge). So Java and SQL are not related in being programming languages.
The two languages are often used together when writing Java applications, as using SQL in this manner allows developers to access data for their applications. Modern-day applications will often abstract as much SQL away from the Java developer by use of an ORM (Object-relational mapper).
What is Java used for?
As discussed, Java is a programming language and can be used to build almost any type of application. Java is heavily used in Android development, web development and desktop applications.
Until 2019, Java was the preferred language for building applications for Android devices. In 2019 Google named Kotlin as the successor for building Android applications.
You often hear of Java used in web development in Spring (or Spring-boot) backends. Spring is a framework for building Java applications. Spring contains tools for creating microservices, web apps, serverless apps, event-driven apps and more.
The Spring boot tool allows users to quickly generate the boilerplate code required for many different types of applications. This can mean that the time to prototype or build a minimal viable product is quite short. Spring boot will embed a web server and application context so the developer can focus on solving the business logic of the task.
This pre-built method of bootstrapping an application reduces the developer’s need to test areas of their solution as they can trust that anything given to them by the spring framework has already been tested.
Java has a toolkit named Swing that is part of the Java Foundation Classes (JFC). This toolkit has everything required to build a cross-platform UI. Using Swing, developers can quickly build desktop applications using powerful pre-defined components.
There are also other desktop-building libraries for Java applications. The other most common way to build desktop applications is to use JavaFX. JavaFX can also be used for mobile development. It allows common web styling using CSS, which makes the styling of JavaFX applications very powerful and easy to understand for any web developer.
What is SQL used for?
SQL is used for communicating with database servers. SQL is a standardised language meaning that any database vendor who implements “SQL” typically does so in a standardised manner. This allows developers to work on many different database varieties and know how to interact with them.
Typically, the standard SQL is extended with any commands that a specific database requires. For example, Oracle databases may have functionality that MS SQL Server does not have, and in this case, Oracle will extend the SQL for their purposes.
SQL allows developers to create, update, read or delete data in a database. For example, a SQL statement could create a table, delete a table, modify the table’s data or even link a column in the table to another table.
SQL also allows developers to set triggers and code that gets executed upon certain events, manage user privileges and set views (among other things). This means that the language doesn’t just allow modifying table data but also managing the system.
SQL and Java are both languages, SQL being a query language and Java being a programming language. They work together when building software applications that need to access data or interact with some database system.