Eclipse project started as a project for developing a development platform for Java code. Even though it is still focused arround Java a lot of additions have been build around Eclipse. Eclipse is as the project like to explain; "a community for individuals and organizations who wish to collaborate on commercially-friendly open source software. Its projects are focused on building an open development platform comprised of extensible frameworks, tools and runtimes for building, deploying and managing software across the lifecycle. "
You can find plugins for large number of languages and for a large number of development frameworks that can be enabled within Eclipse. One of the companies investing in the development of Eclipse plugins is Oracle and as Oracle is a database company they also made sure some code was donated to make Eclipse a SQL development environment. This however is somewhat unknown as Oracle mostly promotes the Oracle SQL Developer solution. However, when you only need to work on SQL code occasionally and do most of your development work in Eclipse this can be very handy. Or,... if you just like Eclipse more then you like Oracle SQL Developer.
To start using the Oracle database plugin for Eclipse you will to undertake the following steps.
Start Eclipse and go to "Windows" - "Open Perspective" - "Other"
Selecting the option from step 1 will provide you with the screen as show below. Here you can select the perspective for database development.
The action performed in step 2 will open a new side menu on the left side of Eclipse and will show as the "Data Source Explorer". At the Database connections menu right-click and select New.
Eclipse is providing a lot of database connection types. If you have installed the Eclipse Oracle additions you will also have the option for an Oracle database. Out of the box a lot of other database connection types are also provide as you can see in the below screenshot.
When you have selected the Oracle database option you will be provided with the below menu where you will have to enter de connection details for this specific database connection.
When you have successfully completed the actions in step 5 and have clicked finish you should now have a working connection and the options to start developing PL/SQL code and start executing commands against your Oracle database. Below is a screenshot showing your Eclipse Oracle SQL worksheet.