Question: How to export Oracle DB data using SQL Developer? I need all data, tables, constraints, structure and so on.

Answer: 
In **version 3**, they changed "**export**" to "**unload**". It still functions more or less the same.
To export data you need to right click on your results and select export data, after which you will be asked for a specific file format such as `insert`, `loader`, or `text` etc. After selecting this browse your directory and select the export destination.